ANSWER
[tex]x = - 3 \: \: or \: \: x = 3[/tex]
The degree is two so it must have more than one solution.
EXPLANATION
The given equation is
[tex] {x}^{2} = 9[/tex]
Let us use the square root method to solve this equation.
Since the degree of x is two, the fundamental theorem of algebra says it must have 2 roots.
We take square root to obtain,
[tex]x = \pm \sqrt{9} [/tex]
[tex]x = \pm3[/tex]
Split the plus or minus sign to obtain,
[tex]x = - 3 \: \: or \: \: x = 3[/tex]
