# How do you solve x^2+8x-5=0 using the quadratic formula?

Jul 4, 2017

$x = - 4 \pm \sqrt{21}$

#### Explanation:

The quadratic formula is $x = \frac{- b \pm \sqrt{{b}^{2} - 4 a c}}{2 a}$

in your formula $a = 1$
$b = 8$
and $c = - 5$

$x = \frac{- 8 \pm \sqrt{{8}^{2} - 4 \cdot 1 \cdot - 5}}{2 \cdot 1}$

$x = \frac{- 8 \pm \sqrt{64 + 20}}{2}$

$x = \frac{- 8 \pm 2 \sqrt{21}}{2}$

$x = - 4 \pm \sqrt{21}$