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!!!