Answer:
Square root of 9² is 9, not 3
Explanation:
x² - 9²
(x - 9)(x + 9)
see below
x^2 - 9^2
We know this is the difference of squares
a^2 - b^2 = (a-b) (a+b)
The second term is 9^2 not 3^2
(x-9) ( x+9)
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