# How do you solve 1 - 4x - x^2=0 using completing the square?

Jul 3, 2015

Solve y = - x^2 - 4x + 1 = 0

#### Explanation:

$y = - \left({x}^{2} + 4 x - 1\right) = 0$

$\left({x}^{2} + 4 x + 4\right) - 4 - 1 = 0$
${\left(x + 2\right)}^{2} = 5$
$\left(x + 2\right) = \pm \sqrt{5}$

$x = - 2 \pm \sqrt{5}$