Question 135843
I think you may have mis-typed the second problem.  I don't see what's being divided.  But I will help you with the first problem.  Your problem is:

{x^2 - 9x + 20} / {x^2 - 16}

This is best solved by factoring both sides.

First the dividend (the left side):  X^2 - 9x + 20 = {x-4}{x-5}

Then the divisor: {x^2 - 16} = {x+4}{x-4}
(this one is "difference of squares" factoring)

So once factored, your original problem is re-written as such:

{{x-4}{x-5}} / {{x+4}{x-4}}

Clearly, the {x-4} cancels on both sides, leaving the answer: <u>{x-5} / {x+4}</u>