Blog 4: Be the Professor

Hi! I'm Professor Sisk and today I will be teaching y'all about everybody's favorite..... Fractions!!!  It is really important to study fractions because they are the foundation of a lot of different math techniques that you will be expected to acquire knowledge of at some point in your life.  For example, algebra.  Algebra would be incredibly difficult to learn without basic knowledge of the addition, subtraction, multiplication, and division of fractions.

First, we will cover the addition and subtraction of fractions.  It's easy!  If the denominators for the fractions you are adding or subtracting are the same, then just add your numerators together.  If there is not a common denominator, you just need to find a common denominator by using cross multiplication and the addition of your uncommon denominators.  Here is an example of simple addition and subtraction of fractions and a variable example to help you understand how to find the common denominator.
ex: a/b + c/b = a+c/b
ex: a/b + c/d = ad+cb/bd

Next, I'll explain multiplication of fractions.  All you need to do to multiply straight across!
Here is a variable example and a numerical example that will show you the exact process.
ex: a/b x c/d = ac/bd
ex: 3/4 x 2/3 + 6/12 or 1/2 !!!

A little jingle to help you remember how to multiply fractions is...
Multiplying fractions ain't no problem.. top times top and bottom...

Finally, the division of fractions!  Dividing fractions is easy too!  You keep the first fractions exactly how it is, and multiply it by the opposite of the second fraction.  Check out these examples.
ex: a/b ÷ c/d = a/b x d/c = ad/bc
ex: 1/2 ÷ 3/2 = 1/2 x 2/3 = 2/6 or 1/3

To remember how to divide fractions sing...
Dividing fractions don't know why.. Flip the second number and multiply!

Together, your jingle should sound like-
Multiplying fractions ain't no problem, top times top and bottom times bottom.  Dividing fractions, don't know why, flip the second number and multiply ! ( but fiiiiiiirst, cross cancel)

You guys should be set!
Thanks
-Professor Sisk