Answer
The solutions are -3 and 3.
Work Step by Step
$x^{2}$=9
$x^{2}$-9=9-9
$x^{2}$-9=0
$x^{2}$-$3^{2}$=0
(x+3)(x-3)=0
x+3=0 or x-3=0
x+3-3=0-3 or x-3+3=0+3
x=-3 or x=3
The solutions are -3 and 3.
Check
Let x=-3
$x^{2}$=9
$(-3)^{2}$ =9
9=9
Let x=3
$x^{2}$=9
$3^{2}$ =9
9=9
0=0
