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Old 2009 June 30th, 02:58 AM   #1 (permalink)
randyse
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Join Date: Jun 2009
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Algebra question

Hello. I'm working the EZ Solutions Test Prep series of books and came across the following Algebra problem. I'll post what they say the answer is with how they arrived at it and the answer I arrived at and how I arrived at it.

Could someone please explain where I went wrong? Even with their explanation I don't get it.

10x2 + 28xy + 18y2
Them:
(5x)(2x) + (+10 + 18)xy + (+9y)(+2y)
5x(2x + 2y) + 9y(2x + 2y)
(5x + 9y)(2x + 2y)

My solution: first I thought I should factor out 2:
2(5x2 + 14xy + 9y2)
2[(5x + 9y)(x+y)]

Where did I go wrong?

Thanks,
Randy
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