How do you factor #81x^2 - 36y^2?

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Answer 1 · 2015-06-21T03:53:22

The answer is $9(3x+2y)(3x-2y)$ .

Factor $81x^2-36y^2$ .

Factor out $9$ .

$9(9x^2-4y^2)$

$(9x^2-4y^2)$ is in the form the difference of squares:

$a^2-b^2=(a+b)(a-b)$

$a=3x;$ $b=2y$

$9((3x)^2-(2y)^2)$ =

$9(3x+2y)(3x-2y)$