Simplify \(\large \dfrac{x^2+x-12}{-x^2-4x+21} \div \dfrac{x+4}{x+7}\)
First, we have to apply the fraction rule, turning it into (x2+x-12)/(-x2-3x+21)(x+7)/(x+4)
We simplify it to be -(x+4)/(x+7)(x+7)/(x+4)
We multiply it to -(x+7)/(x+7)
Simplify that to be -1
Yay!
