x^2 + 8x – 48 = 0
That is a quadratic equation where
a = 1
b = 8
c = -48
We can solve it by using the quadratic formula:
x = [-b +-sq root (b^2 - 4ac)] / 2a
x = [-8 +- sq root (64 -4*1*-48)] / 2*1
x = [-8 +- sq root (256)] / 2
x = [-8 +-16] / 2
x1 = 8 / 2 = 4
x2 = -24 / 2 = -12