Domain of a function

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for g(x) = (x-2) / (x^2 -9)

the domain of the function would be simply to have the denominator not equal to 0, which in this case would be x = 3.

but.. the solution states that it is -3 and 3 cannot be used.

this is confusing seeing that -3^2 -9 = -18 which is not 0.

maybe it means |-3|?
 
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(-3)^2 - 9 = 9-9 = 0

there is a difference,

-3^2 = (-1)*3^2 = -1*9 = -9, but (-3)^2 = (-1*3)^2 = (-1)^2 * 3^2 = 1*9 = 9
 
77
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i get it. thanks
 

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