# How do you solve x^2+10x+9=0 using the quadratic formula?

Oct 25, 2014

The quadratic formula is

$x = \frac{- b \pm \sqrt[2]{{b}^{2} - 4 a c}}{2 a}$

where $a$, $b$, and $c$ are the coefficients of the terms of the quadratic equation

For your equation we have

${x}^{2} + 10 x + 9 = 0$

$\implies x = \frac{- 10 \pm \sqrt[2]{{10}^{2} - 4 \left(1\right) \left(9\right)}}{2 \left(1\right)}$

$\implies x = \frac{- 10 \pm \sqrt[2]{100 - 36}}{2}$

$\implies x = \frac{- 10 \pm \sqrt[2]{64}}{2}$

$\implies x = \frac{- 10 \pm 8}{2}$

$\implies x = \frac{- 10 + 8}{2} , x = \frac{- 10 - 8}{2}$

$\implies x = - 1 , x = - 9$