Answer
$\left\{-2, 6\right\}$
Work Step by Step
The quadratic equation $ax^2+bx+c=0$ can be solved using the Quadratic Formula:
$x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$, for the equation:
The given equation has $a=1$, $b=-4$, $c=-12$.
Using these values and the Quadratic Formula above gives:
$x=\dfrac{-(-4)\pm\sqrt{(-4)^2-4(1)(-12)}}{2(1)}\\
x=\dfrac{4\pm\sqrt{16+48}}{2}\\
x=\dfrac{4\pm\sqrt{64}}{2}\\
x=\dfrac{4\pm8}{2}$
Hence,
$x_1=\dfrac{4+8}{2}=6$
$x_2=\dfrac{4-8}{2}=-2$
