# How do you complete the square to solve x^2 - 2x = 15?

Jun 2, 2015

Given ${x}^{2} - 2 x = 15$ add 1 to both sides to get:

$16 = {x}^{2} - 2 x + 1 = {\left(x - 1\right)}^{2}$

So $x - 1 = \pm \sqrt{16} = \pm 4$

Add $1$ to both sides to get:

$x = 1 \pm 4$

That is: $x = - 3$ or $x = 5$