# How do you solve sqrt(x+9)=6?

Apr 10, 2017

$x = 27$

#### Explanation:

To 'undo' the root $\textcolor{b l u e}{\text{square both sides}}$ of the equation.

${\left(\sqrt{x + 9}\right)}^{2} = {6}^{2}$

$\Rightarrow x + 9 = 36$

subtract 9 from both sides.

$x \cancel{+ 9} \cancel{- 9} = 36 - 9$

$\Rightarrow x = 27$

$\textcolor{b l u e}{\text{As a check}}$

Substitute this value into the left side and if equal to the right side then it is the solution.

$\sqrt{27 + 9} = \sqrt{36} = 6 = \text{ right side}$

$\Rightarrow x = 27 \text{ is the solution}$