Question 243233
Subtract 9 from both sides.
{{{x^2 -9 = 0}}}
I hope you see that you can factor this easily because 9 is a perfect square (3*3), and that you do not need an 'x' value, and that it is -9.
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If you memorized {{{x^2 -1 = (x+1)(x-1)}}} you can substitute any perfect square for the '1'.
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So the solution is,
(x+3)(x-3)=0
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So, x can = 3 or -3.
That is the same as saying the square root of 9 can be either +3 or - 3, which is true.
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That suggests we could have solved the problem by taking the square root of each side first.
{{{sqrt(x^2)=sqrt(9)}}}
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The square root of x^2 is simply + or - x.
The square root of 9 is simply + or - 3.