Chapter 8 - Graphing Quadratic Functions - 8.4 - Graphing f(x) = a(x-h)^2 + k - Exercises - Page 448: 82

The roots are $x=3$ and $x=-3$.

The given equation is $\Rightarrow (3x-9)(4x+12)=0$ Use zero product property rule. $\Rightarrow 3x-9=0$ or $4x+12=0$ Solve for $x$. $\Rightarrow 3x=9$ or $4x=-12$ $\Rightarrow x=\frac{9}{3}$ or $x=-\frac{12}{4}$ $\Rightarrow x=3$ or $x=-3$ The roots are $x=3$ and $x=-3$.