# How do you solve using the completing the square method x^2 + 2x = 35?

Apr 9, 2016

$x = 5$
or
$x = - 7$
(see below for solution by completing the squares)

#### Explanation:

Given ${x}^{2} + 2 x = 35$

Complete the square:
$\textcolor{w h i t e}{\text{XXX}} {x}^{2} + 2 x \textcolor{red}{+ 1} = 35 \textcolor{red}{+ 1}$

Re-write as squared terms
$\textcolor{w h i t e}{\text{XXX}} {\left(x + 1\right)}^{2} = {6}^{2}$

Take square root of both sides:
$\textcolor{w h i t e}{\text{XXX}} x + 1 = \pm 6$

$x = 5 \mathmr{and} x = - 7$