# How do you solve x^2 – 10x – 1 = -10 using the quadratic formula?

Aug 14, 2017

$x = 9 , 1$

#### Explanation:

Given:

${x}^{2} - 10 x - 1 = - 10$

Move all terms to the left side.

${x}^{2} - 10 x - 1 + 10 = 0$

Simplify.

${x}^{2} - 10 x + 9$ $\leftarrow$ Quadratic equation in standard form:

$a {x}^{2} + b x + c = 0$, where:

$a = 1$, $b = - 10$, and $c = 9$.

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

Substitute the given values into the formula.

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

Simplify.

x=10+-sqrt(100-36))/2

Simplify.

$x = \frac{10 \pm \sqrt{64}}{2}$

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

Solutions for $x$.

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

Simplify.

$x = \frac{18}{2} ,$ $\frac{2}{2}$

$x = 9 , 1$