# How do I use the quadratic formula to solve x^2 + 8x = 2?

Sep 30, 2014

$A {x}^{2} + B x + C = 0$

${x}^{2} + 8 x = 2$

${x}^{2} + 8 x - 2 = 0$

$A = 1 , B = 8 , C = - 2$

Quadratic Formula, $x = \frac{- b \pm \sqrt{{b}^{2} - 4 a c}}{2 a}$

$x = \frac{- \left(8\right) \pm \sqrt{{\left(8\right)}^{2} - 4 \left(1\right) \left(- 2\right)}}{2 \left(1\right)}$

$x = \frac{- 8 \pm \sqrt{64 + 8}}{2}$

$x = \frac{- 8 \pm \sqrt{72}}{2}$

$x = \frac{- 8 \pm \sqrt{2 \cdot 2 \cdot 2 \cdot 3 \cdot 3}}{2}$

$x = \frac{- 8 \pm \left(2\right) \cdot \left(3\right) \cdot \sqrt{2}}{2}$

$x = - 4 \pm \left(3\right) \cdot \sqrt{2}$

$x = - 4 \pm 3 \sqrt{2}$