# Math 11 Pre-Calc, Week 15

This week in math we started a new unit, this unit is called multiplying and dividing rational expressions. and example of this is with this equation of

= $\frac{x^2-6x-16}{x^2+4x-21} \frac{x^2+9x+14}{x^2-8x+15}$

since its a divide question u would want to flip the second fraction like this

= $\frac{x^2-6x-16}{x^2+4x-21} \frac{x^2-8x+15} {x^2+9x+14}$

Then u would want to factor it and turn it into a multiplication question

= $\frac {(x+2)(x-8)}{(x-3)(x+7)} x \frac {(x-3)(x-5)}{x+2)(x+7)}$

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 whould get rid of. this will turn the equation into

= $\frac {(x-8)(x-5)}{(x+7)(x+7)}$

now you would want to find the numbers that can’t equal zero on the denominator of the fraction

so that would be X can’t equal -7

and that’s how you solve multiplying or dividing rational equations