# How do you solve  (x+4)^2=81 ?

Jan 25, 2016

There are two possible solutions.

#### Explanation:

You can take the square root on both sides, but you have to remember, that a negative number, when squared, also gives a positive answer. In this case it's not so hard:

${\left(x + 4\right)}^{2} = {9}^{2} \mathmr{and} {\left(x + 4\right)}^{2} = {\left(- 9\right)}^{2}$

So: $x + 4 = 9 \to x = 5$
Or: $x + 4 = - 9 \to x = - 13$

Most people leave out the second solution, so...