Question 305120
How do you simplify 
x^3 - x^2 - 12x
---------------
x^3 - 9x


Let's do the numerator first:

x^3 - x^2 - 12x = x*(x^2 - x -12) =
x*(x-4)*(x+3)

Now the denominator:

x^3 - 9x = x*(x^2 - 9) =
x*(x+3)*(x-3)

Putting these together we have:

(x*(x-4)*(x+3))/(x*(x+3)*(x-3)) =

(x-4)/(x-3)