Sequences

Recognizing Patterns:

Can you find the particular pattern to each of the sequences below? See if you can guess the number that comes next for each set of numbers below!

a) 1, 1, 1, 1, 1, ?
b) 1, 2, 3, 4, 5, ?
c) 2, 4, 6, 8, 10, ?
d) 5, 10, 15, 20, ?

Easy to recognize what comes next, right? But how did you know? What pattern did each example make? That’s what we’ll be talking about in this post, sequences!

What is a Sequence?

Let’s start with a formal definition. A sequence is a list of numbers or objects that are in a particular order and form a pattern. Each example above is a different type of sequence that follows a specific pattern! That’s why we were able to easily find the successive term of each sequence (solution to each example below).

The above examples of sequences are just a snippet of what a sequence can look like, but there are so many sequences that exist! There is even a website that compiles every sequence in the world possible, called The On-Line Encyclopedia of Integer Sequences (OEIS), it’s like a kind of dictionary but for sequences! They also accept new sequences to their website. After reading this post, see if you can come up with your own sequence to add to their encyclopedia!

Types of Sequences:

There are so many different types of sequences! Sequences can take so many different forms, they can be infinite sequence where they can go on forever, or they can be finite sequence where they have an end. A sequence can be based on addition, subtraction, multiplication, division, or even based on the value of the previous term! Let’s take a look at each type of sequence one step at a time with an example for each:

Types of Sequences


Arithmetic Sequence
Geometric Sequence
Recursive Sequence

Finite Sequences


Finite Arithmetic Series
Finite Geometric Series

Infinite Sequences

Infinite Geometric Series

Special Sequences

Fibonacci Sequence
Summing Every number from 1 to 100

Arithmetic Sequence:

Arithmetic sequences are a sequence of numbers that form a pattern when the same number is either added or subtracted to each successive term. Take a look at the example of the of the arithmetic sequence below. Notice we are adding 2 to each term in the sequence 4, 6, 8, 10, … below. The number we add to each term in this sequence (in this case 2), is called the common difference. If we were to find the next term in the example of the sequence below, the next term of the sequence would be 12 (10+2=12).

sequences

Sometimes, we are asked to find not just the next term, but a term further down the line in the sequence. For example, what if we were asked to find the value of the 123rd term? That’s where the arithmetic sequence formula would come in! Check out the explicit formula below:

an=a1+(n-1)d

a1=First Term
n=Term Number in Sequence
d=Common Difference (Number Added/Subtracted to each Term in Sequence)

Now, to find the 123rd term of the above sequence, we would plug in the following values into our formula to solve. Notice the common difference here is still 2, because it is the number we are adding to all the terms in our sequence.

sequences
sequences

Notice the above arithmetic sequence is a an example of an infinite sequence! This means that we can continue finding terms for this sequence forever!

Want another example? For more examples and a step-by-step video on arithmetic sequences, check out the resources here and below:

Geometric Sequence:

Geometric sequences are a sequence of numbers that form a pattern when the same number is either multiplied or divided to each subsequent term. Take a look at the example of a geometric sequence 4, 8, 16, 32, … below. Notice we are multiplying 2 to each term in the sequence below. The number that is multiplied to each term in the sequence is called the common ratio, which in the case of the geometric sequence below is 2. If the pattern were to continue, the next term of the sequence above would be 64, since 32 x 2=64.

sequences

Sometimes, we are asked to find not just the next term, but a term far down the line in the sequence, for example, what if we were asked to find the value of the 15th term? That’s where the geometric sequence formula would come in!

an=a1r(n-1)

a1 = First Term
r=Common Ratio (Number Multiplied/Divided to each Term in Sequence)
n= Term Number in Sequence

To find the 15th term of the above sequence, we would need to plug in the following values into our formula to solve:

sequences
sequences

Notice the above geometric sequence is a type of infinite sequence! This means that we can continue finding terms for this sequence, forever!

Want another example? For more examples and a step-by-step video on geometric sequences, check out the resources here and below:

Recursive Sequences:

A Recursive Formula is a type of formula that forms a sequence based on the previous term value. These can be based on arithmetic sequences or a geometric sequences, the sequence type does not really matter, as long as each successive term is based on the previous term. What does that mean? Check out the example below for a clearer picture:

What are the first 5 terms of a recursive sequence given the following recursive formula:

First, let’s decode what this says:

sequences

Now, let’s see our formula in action! Notice below, we start with the first term, a1=2. Then we use 2 to plug into our formula for the second term to get 2+4=6, and we continue the pattern all the way through for the first five terms, to get our answer.

sequences

Recursive Sequence: Now that have used our recursive formula, notice it gave us this nice, beautiful sequence represented by each term circled in pink above, 2, 6, 10, 14, 18. That is our recursive sequence, and the answer to our question! Notice in this example, we have an infinite sequence that we can keep finding terms for, but since our question asked for the first 5 terms, we stopped here.

Want another example? For more examples and a step-by-step video on recursive sequences, check out the resources here and below:

Finite Sequence and Series:

Now that we have gone over infinite sequences (Arithmetic, Geometric, Recursive), let’s dive into finite sequence and series!

What’s the difference between a sequence and a series? We know what sequences are, but what is this new word “series” all about? Well, what if we had the first 5 terms of a sequence, but now, we want to add them all together? That is a series, more specifically a finite series since we only want to add the first five terms! Another term you might see that describes a finite sequence is “Partial Sum” or “Partial Sums” because we are summing only part of the sequence.

Finite Arithmetic Series:

A finite arithmetic series happens when we take the terms of an arithmetic sequence and we sum a finite number of them together. Basically, we know that the arithmetic sequence gives us the following terms:

But now we want to sum all these terms together:

How would we be able to find the partial sum of the first 20 terms of an arithmetic sequence? Well, we could sit there and crunch our numbers one by one on a calculator, or we could plug them into the arithmetic finite sequence formula below:

Sn=(n/2)(2a1+(n-1)d)

n=Number of Terms we want to Sum

d=Common Difference

a1=First Term

To find the sum of the first 20 terms of the above sequence, we would need to plug in the following values into our formula to solve. Notice that in this case, the common difference is 2, since each subsequent term is being added by 2.

sequences

For more examples and a step-by-step video on how to find the finite length of a Finite Arithmetic Series, check out the resources here and below:

Finite Geometric Series:

A finite geometric series happens when we take the terms of a geometric sequence, and we sum them together. Basically, we know that the geometric series gives us the following terms:

But now we want to sum all these terms together:

How would we be able to find the partial sums of the first 20 terms of a geometric sequence? Well, we could sit there and crunch our numbers one by one on a calculator, or we could plug them into the formula below:

Sn=a1 (1-rn)/(1-r)

a1=First Term

n=Number of Terms we are Summing together

r=Common Ratio

sequences

For more examples and a step-by-step video on finite sequences and Geometric Series, check out the resources here and below:

Infinite Sequences:

An infinite sequence is one in which the sequence just keeps going and going infinitely with no end. We have already seen examples of this earlier in this post when looking at an arithmetic sequence or geometric sequence. But now, we want to ask ourselves, what would happen if we were to add an entire infinite sequence, by adding together each term within the sequence?

When it comes to adding an infinite arithmetic sequence together, the arithmetic sequence always diverges to infinity. On the other hand, an infinite sequence that is also a geometric sequence, can either diverge to infinity, or converge to a number. If the idea of converging or diverging to infinity, doesn’t make sense yet, that’s ok, keep reading and we’ll go over everything!

Infinite Geometric Series:

An infinite geometric series happens when we take the terms of a geometric sequence, and we sum them together, all of them together, starting with the first term, going all the way to infinity. Basically, we know that the geometric series gives us the following terms:

But now we want to sum all these terms together, from the first term all the way to infinity.

But wait, how do we know if it is even possible to sum together a geometric sequence starting with the first term and adding until infinity? Well, it all depends on divergence vs. convergence. If the common ratio is between -1 and 1, that means that the sum to infinity will converge and we can find the value of the sum of an infinite geometric sequence. If the common ratio has any other value otherwise it will diverge to infinity.

* If you need a review on how to use Summation Notation, check out this link here!

*Also here is a reminder of what a geometric sequence looks like, for anyone who needs it!

sequences

Now, let’s see if the following geometric series converges or diverges:

Since, we know it converges based on the common ratio, we know we can find the value of the infinite sum! Let’s use the formula below:

Sn=a1/(1-r)

a1=First Term

r=Common ratio

Next, let’s plug in our value into the formula:

sequences

For more examples and a step-by-step video on Infinite Geometric Series, check out the resources here and below:

Special Sequences

Fibonacci Sequence – The Most Famous Sequence!

The above sequence, known as the “Fibonacci Sequence,” is the most famous sequence in the world! How can a sequence be so famous? Why is it so special? Well, we’ll get to that in a minute, but before we do, can you see how the Fibonacci Sequence forms a pattern? What would be the next term?

Take your time, trying to figure out the next term of the sequence before taking a peak at the answer below:

Why!? Solution Explained

The next term of the Fibonacci sequence is 21! The pattern of this famous sequence is all about adding the two previous terms together. That’s how we get 1+1=2, 1+2=3, 2+3=5, 3+5=8, 5+8=13, which brings us to get our missing term, 8+13=21. Take a look at how this sequence works below:

Why is the Fibonacci Sequence Famous?

Now that we know the secret pattern behind this sequence, let’s look at why the Fibonacci sequence is so special! The Fibonacci sequence’s main claim to fame is that it is found throughout art, architecture and even in nature via the golden ratio.

The Golden Ratio is a proportion that is considered to be the most pleasing ratio to the human eye! You may also know the Golden Ratio as the golden mean, the divine proportion, phi, or the Greek letter ϕ. It is an infinite and irrational number that approximates to 1.618 and is found by adding two numbers together and then dividing by the larger number and if these same two numbers are then set equal to the larger number divided by the smaller number successfully, then the two numbers are a golden ratio equal to 1.618! If this sounds too confusing to imagine, just take a look at the formula below:

Is it a Golden Ratio?

If the following formula holds true, then yes!

What is amazing about this ratio, is that it can be related back to the Fibonacci Sequence!

The Golden Ration + Fibonacci Sequence:

If we were to take the sequential numbers found within the Fibonacci sequence (1,1,2,3,5..), and plug them into the golden ratio formula above, it would approximate to the golden ratio value, 1.618, the further along in the sequence we go.

The Golden Ratio + Art + Architecture + Nature:

If we were to draw a rectangle that has golden ratio proportions, we would get the golden rectangle below.

Let’s draw a golden rectangle, within our golden rectangle to see what happens:

What happens if we continue this specific pattern and keep drawing in golden rectangles within itself?

Until eventually we get something like this….

The proportion between the width and height of these rectangles is 1.618 and can also be shown as the proportion between any two numbers in the Fibonacci sequence as the sequence approaches infinity.

The above pattern, when all lines are connected form a spiral that can be found within art, architecture, and nature itself! Below we have a picture of the Parthenon, the Mona Lisa, a shell, and the Taj Mahal.

The Golden Ratio + YOU:

Want to know if you yourself has a face that fits the golden ratio?! Try measuring your face horizontally and vertically and plug in those values into the golden ratio formula, dividing the larger number by the smaller number. What did you get? Something close to 1.6 maybe!?

The Golden Ratio + Resources:

If you’re looking to learn more about the Golden Ratio, be sure to check out these resources here.

Donald Duck’s – Mathmagic Land:

Video shows how the golden ratio works and where we can find it! https://www.youtube.com/watch?v=U_ZHsk0-eF0&t=1s

Investopedia + Golden Ratio:

Learn how the Fibonacci Sequence connects to the modern-day stock market! https://www.investopedia.com/articles/technical/04/033104.asp

The Golden Ratio + Mathematics:

Learn where you will see the Golden Ratio in mathematic equations and shapes!
https://www.mathsisfun.com/numbers/golden-ratio.html

Summing Numbers from 1 to 100:

Now that we’ve discussed the most famous sequence, let’s talk about the most well-known sequence, which are just plain old-fashioned natural numbers, starting at 1 and counting to infinity! The sequence we all grew up with and learned to love, yes, natural numbers:

1,2,3,4,5, ….100, …..

What if we were tasked with summing all the numbers from 1 to 100? How would we do that? Well, believe or not, there is a formula to adding all of these numbers together, that was discovered by a famous mathematician named Johann Karl Friedrich Gauss. Apparently, he came up with this pattern after being assigned to add all the numbers from 1 to 100 as an elementary school student! The teacher thinking this would be perfect “busy” work for her class did not see it coming!

How to Sum 1 to 100:

Gauss found a pattern, when adding together the numbers 1 to 100. He looked at the big picture, recognizing that the sum between pairs of numbers from the beginning of the sequence and at the end of the sequence were the same throughout the entire list of numbers! For example, 1+100=101, 2+99=101, 3+98=101, and this pattern continues between all the numbers from 1 to 100! Take a look:

Formula and Solution:

Noticing this pattern, lead Gauss to come up with the following formula to sum every number from 1 to 100:

Above we use the formula to sum every number from 1 to 100 but it can be used to find other sums as well! If you’re wondering where in the world the above formula even came from, try testing it out with a smaller sum, summing numbers from 1 to 10 and see what happens!

Just like we find the sum in an arithmetic or geometric series, we can find the sum of other types of sequences, as we see here with natural numbers! We can even realize that summing numbers 1 to 100 is like summing an arithmetic sequence with a common difference of 1. Hidden patterns and formulas are used to solve all different types of sequences we haven’t even gone over in this post. But let this post guide you with the basics! See if you can find the pattern of any sequences that you find (in this post, in class, or in the street walking around, as sequences are found there too).

If you’re looking for more resources, check out this website that connects Gauss’s Summation formula to arithmetic sequences found in the real world here.

I hope you find this overview of sequences helpful! If there is anything you’d like me to go over more or if you have any questions, please let me know in the comments. Also, please check us out on social media for the latest MathSux videos, lessons, practice, questions, cheat sheets, and more! Happy calculating!

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How to Make a Paper Cube Using Origami

Greeting math peeps and welcome to MathSux! In today’s post, we are going to have a bit of fun when finding the volume of a cube. We’ll start by going over how to make a paper cube using origami, then we will measure the dimensions of our real-world cube and find its volume. Hope you’re all feeling crafty and ready to take on this project with the Japanese art style of origami! If you don’t have any origami paper, please fill free to print out the origami guideline sheets included at the end of this post to follow along! Also, if the below written tutorial isn’t your style, watch the video up on YouTube and shown below. Hope you’re all having a great week and can find some fun in this post! Happy calculating!

How to Make a Paper Cube Using Origami:

How to Make a Paper Cube Using Origami

Step 1: Begin with six sheets of square origami paper (or cut out a square from any type of regular computer paper). If you want to really follow along, this paper is 4 inches by 4 inches and I have included a print out below.

How to Make a Paper Cube Using Origami

Step 2: Fold the top of the origami paper in half, then unfold.

How to Make a Paper Cube Using Origami

Step 3: Fold one side of the paper halfway to the center.

How to Make a Paper Cube Using Origami

Step 4: Fold the left side to the center of the paper and rotate the paper horizontally.

How to Make a Paper Cube Using Origami

Step 5: Take the bottom right corner and fold it to the top center point of the rectangle.

Math and art

Step 6: Now fold the top left corner and bring it to the bottom edge, so both folds align in the middle.

Math and art

Step 7: Next, Open both folds towards the center, undoing our last two steps.

geometry and origami

Step 8: Open the first flap on top, and fold in the top right triangle.

Math and art

Step 9: Unfold the bottom flap, and fold in the bottom left triangle.

Geometry and paper folding

Step 10: Now, we are going to fold down the top left corner to the center of the paper (just above the bottom flap).

Origami

Step 11: Fold up the bottom flap.

Math and Origami

Step 12: Now take the bottom right corner, and tuck it in under the top flap, towards the center.

geometry and origami

Step 13: Flip your piece of paper around.

How to Make a Paper Cube Using Origami

Step 14: Fold the corner, towards the center.

How to Make a Paper Cube Using Origami

Step 15: Now, fold in the bottom left edge, towards the center, to the top edge.

How to Make a Paper Cube Using Origami

Step 16: Unfold, the left and right edges we made to get a shape like we have above.

How to Make a Paper Cube Using Origami

Step 17: Repeat steps 1 through 16 5 more times! To have a total of six of the above shapes. We will need all of them to piece together our origami cube.

How to Make a Paper Cube Using Origami

Step 18: Connect each of our shapes, by placing the edge of each in top left the corner “pocket” of each shape.

How to Make a Paper Cube Using Origami

Step 19: Once they are all connected, we finally have created our origami cube!

Want to follow along with everything!? Check out the printable origami paper below to create your very own box!

Volume of a Cube:

Now that we have made our cube using paper folding, we can measure one side of our cube and find its volume! Please note that these measurements are based on the 4″X 4″ origami paper I used. If you would like to follow along with your own project, just download and print the activity sheet above!

Volume of a Cube

Did you create your origami cube with different-sized origami paper? Let us know what measurement you got for volume in the comments below!

Looking for more Origami + Math? Check out this post here to fold and find the volume of a real-world pyramid and rectangular prism.

What is your favorite way to combine math and the real world? Or math and art in general? Let me know in the comments and happy calculating!

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3 Equations 3 Unknown

Hi everyone and welcome back to MathSux! This week we are going to explore how to solve 3 equations 3 unknown. This is like the simultaneous equations we learned to love in Algebra, but now, on steroids. Previously, in algebra we only had to solve for two unknown variables and were given two equations. But now, in Algebra 2, we are faced with three simultaneous equations, as well as, three unknown variables (usually x,y, and z) that we must find the values of. These types of problems can look scary, but with the method of elimination and some practice, they are not so bad! Check out the video, step by step tutorial, and practice problems below to master this topic. Good luck and happy calculating!

What are 3 Systems of Equations with 3 Unknown Variables?

Three systems of equations happen when there are three equations (usually with three unknown variables) are graphed or shown algebraically.  The graph can be represented by using the variables x,y,z (one for each of the three missing variables).  We are all used to the 2-dimensional coordinate plane with X going across and Y going up and down.  But now, with a new unknown variable, z, this gives us a new 3-dimensional axis. Instead of graphing lines like we are used to, these equations are going to be graphed as 3-dimensional planes. 

As for finding the solution to a system of three equations, it is the same for any simultaneous equation, as the answer lies where all three planes intersect.  Below is an example of what a three-dimensional plane can look like when graphed. Don’t worry, typically you wont be asked to graph or even interpret anything like the picture below.

Instead of graphing, typically we are asked to find the solution using algebra! There are three equations and three unknown variables. How are we supposed to know and find the value for each variable?  Well, there are more than one way to solve these types of problems, but in this blog post and in the video above, we will be going over the elimination method.  This is the fastest and easiest way to solve for 3 unknown variables by hand.

Solving by Elimination

3 Equations 3 Unknown

The main idea of Elimination is to pick two pairs of equations and add them together with the goal of canceling out the same variable. We do this by lining up both equations one on top of the other and adding them together.  If a variable or variables does not easily cancel out at first,  we then multiply one of the equations by a number so it will cancel out.

For example, adding the first equation (2x+2y+z=20) and second equation (-3x-y-z=-18) will quickly cancel out z. When we pick another pair of equations to add, picking the second equation (-3x-y-z=-18) and the third equation (x+y+2z=16), we will also have to goal of canceling out z. Once z has been eliminated twice, it provides us with an opportunity to add together the two new equations we just found and eliminate even further to find the value of each unknown variable.  If this sounds like a confusing mouthful, do not worry! We’ll go over this process step by step below.

Check out how it’s done step by step below!

Step 1: First, let’s take another look at our equations and number them so we can keep track of which equations we’re using and when.

3 Equations 3 Unknown

Step 2: Now let’s pick two equations and try to eliminate one of the variables.  If we look at the first two equations (labeled 1 and 2) above, notice we can easily cancel out at the unknown variable z.

3 Equations 3 Unknown

Step 3: Ok great, what now?  Now we are going to take a different pair of our original equations and have the same goal of canceling out the same unknown variable z (just like we did in in the previous step).  Let’s pick the last two equations from above, (labeled 2 and 3). Notice that these two equations do not easily cancel out unknown variable z, therefore, we must multiply 2 times the whole of equation 2 so that they do cancel each other out. 

3 Equations 3 Unknown

Step 4: Now, that we’ve canceled unknown variable z from two different pairs of equations, we can use the two new equations we found in steps 2 and 3 (hi-lighted in purple) to cancel out another variable.

3 Equations 3 Unknown

Step 5: Now that we have the value of one variable, x=3, we can plug it into one of our equations that we used in step 4.

Step 6: Last but not least, let’s find the value to our last unknown variable, z, by plugging in x=3 and y=5 into one of our original equations at the beginning of this example.

Was the wording a bit much? Too many things!? Don’t worry, check out the video and see how this questions gets worked through step by step on a piece of paper. And, if you get the example above, please check out the practice questions below!

Practice Questions:

Find the values of each three variables for each system of equations:

Solutions:

Want more MathSux?  Don’t forget to check out our Youtube channel and more below! And if you have any questions, please don’t hesitate to comment below. Happy Calculating!

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*Bonus* Are 3 equations 3 unknown variables at the same time too much to handle? Check out how to find two simultaneous equations here!

How to Construct the Altitudes of a Triangle ⊿

Hi everyone and welcome back to another week of MathSux! For this week’s math lesson, I bring to you four constructions in one in How to Construct the Altitudes of a Triangle. In the video below, we will:

  • Define what an altitude is
  • Find the altitude of an acute, obtuse, and right triangles
  • Discover and define the orthocenter

I hope you find the below video helpful and interesting! Let me know in the comments below and happy calculating!

How to Construct the Altitudes of a Triangle :

An Altitude is a perpendicular line drawn from the vertex of a triangle to the opposite side, creating a 90º angle.

How to Construct the Altitudes of a Triangle

In the video above, we will look at how to find the altitude of an acute obtuse, and right triangle.

How to Find the Orthocenter of Triangle with a Compass:

The Orthocenter is a point where all three altitudes meet within a triangle.

How to Construct the Altitudes of a Triangle

In order to find the orthocenter using a compass, all we need to do is find the altitude of each vertex. The point at which they meet is the orthocenter. Check out the video above to see how this works step by step.

More Constructions?

If you’re looking for more constructions out there, be sure to check out the MathSux Constructions Playlist on YouTube for even more tutorials! I hope you find this video helpful and hope it motivates you to learn even more about constructions (or you know get through your homework/pass that test). Whatever reason you have to learn about constructions I hope this helps! Stay positive and happy calculating!

Best Geometry Tools!

Looking to get the best construction tools? Any compass and straight-edge will do the trick, but personally, I prefer to use my favorite mini math toolbox from Staedler. Stadler has a geometry math set that comes with a mini ruler, compass, protractor, and eraser in a nice travel-sized pack that is perfect for students on the go and for keeping everything organized….did I mention it’s only $7.99 on Amazon?! This is the same set I use for every construction video in this post. Check out the link below and let me know what you think!

Still got questions? No problem! Don’t hesitate to comment with any questions below.

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And if you’re looking for even more geometry constructions, check out the link here!

Derivatives Practice Questions

Hi everyone and welcome to MathSux! In this weeks post, we will venture into Calculus for the first time! I won’t get too much into the nitty gritty explanation of what derivative are here, but instead will provide a nice overview of Derivatives Practice Questions. This post includes everything you need to know about finding the derivatives of a function including the Power Rule, Product Rule, Quotient Rule, and the Chain Rule. Below you will see examples, a Derivative Rules Cheat Sheet, and of course practice questions! I hope these quick examples help in the classroom or for that test coming up! Let me know if it helps and you want more Calculus lessons. Happy Calculating!

What is a Derivative?

We use the derivative to find the rate of change of a function with respect to a variable. You can find out more about what a derivative is and its proper notation here at mathisfun.com. Read on below for a derivative rules cheat sheet, examples, and practice problems!

Derivative Rules Cheat Sheet:

Power Rule:

The power rule is used for finding the derivative of functions that contain variables with real exponents.  Note that the derivative of any lone constant number is zero.

derivatives of functions with exponents

Product Rule:

The product rule is used to find the derivative of two functions that are being multiplied together.

derivatives practice questions

Quotient Rule:

Applying the quotient rule, will find the derivative of any two functions set up as a ratio.  Be sure to notice any numbers or variables in the denominator that can be brought to the numerator (if that’s the case, can use the more friendly power rule).

derivatives of trigonometric functions

Chain Rule:

The chain rule allows us to find the derivative of nested functions. This is great for trigonometric functions and entire functions that are raised to an exponent.

calculus chain rule examples

Ready for some practice questions!? Check out the ones below to test your knowledge of derivatives!

Derivatives Practice Questions:

Find the derivatives for each function below.

Derivatives Practice Questions

Solutions:

Still got questions? No problem! Don’t hesitate to comment with any questions or check out the video above. Happy calculating! 🙂

*Also, if you want to check out Rate of Change basics click this link here!

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NYS Regents Review – Algebra June 2021

Greetings math friends! Today we are going to break down the NYS Regents, specifically the Algebra NYS Common Core Regents from June 2021, one question at a time. The following video playlist goes over each and every question one step at a time. I’ve been working on this playlist slowly adding new questions and videos every week and now that it is complete, it is time to celebrate (and/or study)! Please enjoy this review along with the study aids and related links that will also help you ace the NYS Regents. Happy calculating!

NYS Regents

NYS Regents – Algebra June 2021 Playlist

Study Resources:

Looking to ace your upcoming NYS Regents!? Don;t forget to check out the resources below, including an Algebra Cheat Sheet, and important topics and videos to review. Good luck and happy calculating!😅

Algebra Cheat Sheet

Combing Like Terms and the Distributive Property

How to Graph an Equation of a Line

Piecewise Functions

NYS Regents – Algebra 2020

How to Study Math?

How is one supposed to study math!? Well, there is usually only one way, and that is to practice, practice, practice! But don’t get too stressed, because you can also make practice fun (or at least more pleasant).

Add some background music to your study session and make a nice cup of tea before diving in for the brain marathon. Another idea is to study only 1 hour at a time and to be sure to take breaks. Can’t seem to get that one question? Take a break and walk a way, or even better find a new study spot! It’s been scientifically proven that studying in different places can boost your memory of the very information you’re trying to understand.

What study habits do you have that have worked for you in the past? Let me know in the comments and good luck on your upcoming test!

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** Be sure to check out the full list of Algebra lessons and old Regents questions review!**

Legs of a Right Triangle (when an altitude is drawn)

Greetings math peeps and welcome to another week of MathSux! In todays post we are going to explore how to find the legs of a right triangle when an altitude is drawn from the vertex to its hypotenuse. We are going to take this step by step on how to solve a problem like this. Although, I go over the long way to solve this problem, there is also short cut many people use called the “geometric means” which is also briefly mentioned in this post (under the Tip! section). Whichever method you choose, do what makes most sense to you! Happy calculating!

Similar Right Triangles (with Altitude drawn):

When two triangles have equal angles and proportionate sides, they are similar.  This means they can be different in size (smaller or larger) but if they have the same angles and the sides are in proportion, they are similar! Triangles can be proven similar by AA, SAS, or SSS. For more on similar triangles, check out this post here.

There is a special type of scenario that happens with similar right triangles. When an altitude is drawn from the vertex of a right triangle, it forms two smaller triangles, which creates three right triangles that are similar to the original triangle, based on Angle Angle (AA). Check out the example to see how it works!

In triangle ABC, an altitude is drawn from angle A to its hypotenuse BC. Notice that this creates three 90º right triangles in total (ABC, ABD, and ADC). 

Drawing an altitude created three total right triangles, broken out below:

If you take a closer look, at the triangles above you’ll notice that these two new triangles (ABD and ADC) share an angle with the original bigger triangle ABC and a 90º angle. This makes each of the new triangles similar to the original triangle by AA. We can therefore say that:

How are the New Right Triangles Similar?

1) Triangle ABC ~ ADC

2) Triangle ABC ~ ADB

Ready for an Example?  Lets check out the one below!

Legs of a Right Triangle

Step 1: To find the length of the missing legs of a right triangle, first, let’s separate each right triangle to see what we’re working with, along with the values of each length that was provided.

Legs of a Right Triangle

Step 2: We want to find the length of side AC, so let’s use the triangles whose sides include AC.  This leads us to use triangles ABC and ADC.

Legs of a Right Triangle

Step 3:  Now, let’s set up our proportion to find our missing side.  To make it easier for ourselves let’s first flip and rotate triangle ADC to line up with triangle ABC.

Legs of a Right Triangle
Legs of a Right Triangle

Think you’re ready to try some practice questions on your own? Check out the ones below!

Practice Questions:

Solutions:

Still got questions? No problem! Don’t hesitate to comment with any questions below. Thanks for stopping by and happy calculating!

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Check out more posts on Similar Triangles here!

Sum of Infinite Geometric Sequence

Hey math friends and happy Wednesday! Today we are going to take a look at how to find the sum of infinite geometric sequence (aka series) in summation notation. This may sound complicated, but lucky for us there is an already existing formula that is ready and easy for us to use! So, let’s get to it! Also, don’t forget to check out the video and practice problems below for even more. Happy calculating! 🙂

Looking to review different types of sequences? Check out this post here!

What does it mean to find the “Sum of Infinite Geometric Sequence” (Series)?

We already know what a geometric sequence is: a sequence of numbers that forms a pattern when the same number is multiplied or divided to each term.

Example:

But when what happens if we wanted to sum all the terms of our geometric sequence together?

Example:

We can also write our infinite geometric series using Summation Notation:

How would we calculate that?  That’s where our Infinite Geometric Series formula will come in handy! But before we find a solution, lets take a closer look at what geometric series qualify for this formula.

Divergence Vs. Convergence:

There are two types of Infinite Geometric Series:

Type 1: Infinite Geometric Series that diverges to infinity

Type 2: Infinite Geometric Series that converges to a numeric value (-1 < r < 1)

Check out the differences in the example below:

Infinite Geometric Series Formula:

Note that the below infinite geometric series formula can only be used if the common ratio, r, is less than 1 and greater than -1. If the common ratio, r, is not between -1 and 1, then the sum of the geometric sequence diverges to infinity (and the formula cannot be used).

Now that we have a formula to work with and know when to use it (when -1 < r < 1), let’s take another look at our question and apply our infinite geometric series formula to find a solution:

Sum of Infinite Geometric Sequence

Step 1: First, let’s identify the common ratio to make sure that its between -1 and 1.

Sum of Infinite Geometric Sequence

Step 2: Now that we know we can use our formula, let’s write out each part and identify what numbers we are going to plug in.

Sum of Infinite Geometric Sequence

Step 3: Now let’s fill in our formula and solve with the given values.

Sum of Infinite Geometric Sequence

Practice Questions:

State if each series converges or diverges, then if applicable find the solution.

Sum of Infinite Geometric Sequence

Solutions:

Still got questions? No problem! Don’t hesitate to comment with any questions or check out the video above. Happy calculating! 🙂

*Also, if you want to check out Finite Geometric Series click this link here! And if you want to learn about even more sequences, check out the link here!

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Mobius Bands

Greeting math friends and welcome to another fabulous week of MathSux! Today we are going to look at how to make a Mobius Strip otherwise known as “mobius bands.” Whatever you call them, they are a one of a kind shape that leads to all sorts of questions and math exploration. So let’s get to it! Let’s start off by explaining what a mobius strip is:

What are Mobius Bands?

A mobius strip (or band) is a two-dimensional shape that only has one surface.  Invented by German mathematician August Ferdinand Mobius and also independently by Johann Benedict Listing in the 1800s, it is considered a mathematical phenomenon! We are going to create our own mobius strip today to understand why this shape is so fascinating!

*Note: You may also see different spelling of the mobius band: including Möbius or Moebius

How to Make a Mobius Strip:

Mobius Bands

Step 1: First, let’s gather out materials. For this activity we will need a piece of paper, scissors, tape, and a pencil.

Mobius Bands

Step 2: Let’s cut out a rectangle. The size of the one shown above is 11 X 1 inches. Once you have your rectangle, take one end of the rectangle and give it a half twist.

Mobius Bands

Step 3: Now take the half twisted piece and attach it to the other end of the rectangle with a piece of tape. Behold the beauty of our mobius strip!

How to make a mobius strip

Step 4: Now we are going to take a pen or pencil and draw a line going all around the mobius strip without lifting the pen. See if you can move he mobius strip along, while the pencil remains where it is.  Notice anything special happen? We created a line around the entire shape without lifting our pencil!

Real-World Mobius:

Have you been pondering where we can find Mobius bands in the real world? I thought so! Take a look at the list below:

  • Printer ink cartridges
  • Serpentine Belt in a car
  • VHS tapes (if anyone remembers or knows what those are)
  • Can you think of anymore? Let me know in the comments below!

Worksheet:

I also made this FREE worksheet to go along with the above video and lesson for anyone interested. Let me know if this is helpful! 🙂

If you’re looking for more fun math projects, check out my “Just for Fun” page here. And if you want to get to see the latest MathSux content, don’t forget to follow along with us and subscribe via the links below. Thanks so much for stopping by and happy calculating! 🙂

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How to Find Expected Value

Greeting math friends! Today, we are going to dive into statistics by learning how to find the expected value of a discrete random variable. To do this we will need to know all potential numeric outcomes of a “gamble,” as well as be able to repeat the gamble as many time as we want under the same conditions, without knowing what the outcome will be. But I’m getting ahead of myself, all of this will be explained below with two different examples step by step! Don’t forget to check out the video and practice questions at the end of this post to check your understanding. Happy calculating! 🙂

What is Expected Value?

Expected Value is the weighted average of all possible outcomes of one “game” or “gamble” based on the respective probabilities of each potential outcome.

Expected Value Formula: Don’t freak out because below is the expected value formula.

How to Find Expected Value

In essence, we are multiplying each outcome value by the probability of the outcome occurring, and then adding all possibilities together!  Since we are summing all outcome values times their own probabilities, we can re-write the formula in summation notation:

How to Find Expected Value

Does the above formula look insane to you?  Don’t worry because we will go over two examples below that will hopefully clear things up! Let check them out:

Example #1: Expected Value of Flipping a Coin

Step 1:  First let’s write out all the possible outcomes and related probabilities for flipping a fair coin and playing this game.  Making the below table, maps out our Probability Distribution of playing this game.

How to Find Expected Value

Step 2: Now that, we have written out all numeric outcomes and the probability of each occurring, we can fill in our formula and find the Expected Value of playing this game:

How to Find Expected Value

Ready for another?  Let’s see what happens in the next example when rolling a die.

Example #2: Expected Value of Rolling a Die

Step 1:  First let’s write out all the possible outcomes and related probabilities for rolling a die. In this question, we are assuming that each side of the die takes on its numerical value, meaning rolling a 5 or a 6 is worth more than rolling a 1 or 2.  Making the below table, maps out our Probability Distribution of rolling the die.

How to Find Expected Value

Step 2: Now that, we have written out all numeric outcomes and the probability of each occurring, we can fill in our formula and find the Expected Value of playing this game:

How to Find Expected Value

Check out the practice problems below to master your expected value skills!

Practice Questions:

(1) An unfair coin where the probability of getting heads is .4 and the probability of getting tails is .6 is flipped.  In a game where you win $10 on heads, and lose $10 on tails, what is the expected value of playing this game?

(2) An unfair coin where the probability of getting heads is .4 and the probability of getting tails is .6 is flipped.  In a game where you win $30 on heads, and lose $50 on tails, what is the expected value of playing this game?

Solutions:

Still got questions? No problem! Don’t hesitate to comment with any questions below. Thanks for stopping by and happy calculating! 🙂

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Looking for something similar to Expected Value? Check out the statistics page here!