# Week 15 – Multiplying and dividing rational expressions

This week in pre-calc we learned how to multiply and divide rational expressions together.

You always want to state your non-permissible values first.

For multiplying, the first step to make simplifying your answer easier is to start by reducing your expression with a common factor. Doing this makes multiplying the numbers together a smaller answer and seems better. To reduce with a common factor, you need to use the numerator and find a common factor with a denominator from another expression.

After you’re done reducing your fractions, you can multiply straight across, numerator x numerator and denominator x denominator. Once you’re done that, you can see if you can simplify any more and get the lowest possible fraction.

If you can factor the expression, start by doing that and if you can cancel out terms that are exactly alike, you can make your multiplying easier.

When it comes to dividing, you want to state the non-permissible values of only the terms after the 1st one. After stating those, you want to flip the second fraction and then factor it out. Once you do that you can cancel exact terms and multiply throughout.

It’s important to remember you cannot factor and cancel out terms then flip the second fraction because you will get a completely different answer from the right one.