# How do you solve -4x^2+x+9=0 using the quadratic formula?

Jul 7, 2016

$x = \frac{1}{8} + \frac{\sqrt{145}}{8}$ or $x = \frac{1}{8} - \frac{\sqrt{145}}{8}$

#### Explanation:

The Quadratic Formula is $\frac{- b \pm \sqrt{{b}^{2} - 4 a c}}{2 a}$

A Quadratic Equation is $a {x}^{2} + b x + c = 0$

For the equation $- 4 {x}^{2} + x + 9 = 0$

$a = - 4$
$b = 1$
$c = 9$

Plug in the values

$\frac{- 1 \pm \sqrt{{1}^{2} - 4 \left(- 4\right) 9}}{2 \left(- 4\right)}$

$\frac{- 1 \pm \sqrt{1 + 144}}{- 8}$

$\frac{- 1 \pm \sqrt{145}}{- 8}$

$\frac{- 1}{-} 8 \pm \frac{\sqrt{145}}{-} 8$

$\frac{1}{8} + \frac{\sqrt{145}}{8}$ or $\frac{1}{8} - \frac{\sqrt{145}}{8}$