# Week 15 – Pre Calculus 11

This week in Pre Calculus 11 we were introduced to the concept of dividing and multiplying rational expressions. The first step to solving these expressions is to simplify as much as possible. Doing this it will save you lots of unnecessary steps down the road. Just like in dividing fractions the main this you must remember is to make is a reciprocal value and switch the division to multiplication.

Below you will see an example of a division question:

$frac x^2-6x-16x^2+4x-21 fracx^2+9x+14x^2-8x+15$

since this is a division question you need to flip the second fraction to its reciprocal value

$frac x^2-6x-16x^2+4x-21 frac -8x +15x^2 + 9x + 14$

Now turn it into a simple multiplication question

\$latex frac (x+2)(x-8)/(x-3)(x-7)*frac(x-3)(

now since everything is factored you want to get rid of the factors that are the same so the (x+2) and the (x-3) is something that you would get rid of. this will turn the equation into

\$latex frac (x-8)(x-5)/(x+7)(x+7)

And now you solve for x you can find your nonpermissible values.