Question 328254
The first step is to isolate x.

{{{x^2 - 9 = 0}}}

Add 9 to both sides yielding:


{{{x^2 - 9 + 9 = 0 + 9}}}

Simplify:

{{{x^2 = 9}}}

To undo the squaring operation we must take the square root of x and take the square root of 9 as well.

{{{sqrt (x^2) = "+ or -" sqrt (9)}}}

Now we have:

{{{x = "+ or -" sqrt (9)}}}

x = + or - 3.

Check our solutions by plugging our x values into the original equation:

{{{x^2 - 9 = 0}}}

Where x = 3

{{{(3)^2 - 9 = 0}}}

9 - 9 = 0 Yes!!!

and 
Where x = -3

{{{(-3)^2 - 9 = 0}}}

*Remember any negative number squared yields a positive answer.

9 - 9 = 0 Yes!!!

Good Luck :-)