simple but cnt understand

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simple but cnt understand

by manasi_sh » Sun Oct 07, 2007 7:30 am
Is x2 equal to xy?
(1) x2 – y2 = (x + 5)(y - 5)
(2) x = y
Ans B..
x2= x square and y2 = y square

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by santsark » Tue Oct 09, 2007 11:00 pm
From 1 you can get the value of Y, which is not sufficient to prove X^2 = XY.

But from 2 we know X=Y, so XY = X*X = X^2.