Answer
$x = -7, 2$
Work Step by Step
$8x^{2} + 40x - 112 = 0$
$8(x^{2} + 5x - 14) = 0$
Find two numbers that can be multiplied together to get $-14$ and can be added together to get $5$.
$= -2$ and $7$
$8[x^{2} -2x + 7x - 14] = 0$
$8[x(x-2) + 7(x-2)] = 0$
$8(x+7)(x-2) = 0$
$x = -7, 2$