How do you factor completely $9x^2 - 25y^2$ ?

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Answer 1 · 2015-11-13T20:36:13

$(3x-5y)(3x +5y)$

Given: $9x^2 -25y^2$

The temptation is to do the following:
$9->3^2$
$25->5^2$

Using this we have:

$((3x)^2 -(5y)^2)$

$=> (3x-5y)(3x +5y)$

Does this work?

Check:

$9x^2 -15xy+15xy-25y^2$

Yep! This has to be the answer!!!

How do you factor completely 9x^2 - 25y^29x^2 - 25y^2?