algebra - quadratic equation

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algebra - quadratic equation

by jopup » Sun Jun 22, 2008 2:29 am
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why is one sufficient?

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by Stuart@KaplanGMAT » Sun Jun 22, 2008 8:30 am
Let's start by expanding the expression:

(x^2 + 2xy + y^2)/(x^2 -2xy + y^2)

Now, let's rearrange things a bit:

(x^2 + y^2 + 2xy)/(x^2 + y^2 - 2xy)

Now, let's substitute the info from (1) into the expression:

(3xy + 2xy)/(3xy - 2xy) = 5xy/xy = 5... sufficient!
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