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colakumarfanta
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Last edited by colakumarfanta on Thu May 27, 2010 6:27 am, edited 1 time in total.
From 1
x-y+ (x-y)/xy=0
or (x-y)(1+1/xy)=0
since x is not equal to y, 1+1/xy=0 or xy=-1...sufficient
From 2
(x + y) ^ 2 = x ^ 2 + y ^ 2-2
or x^2+y^2+2xy=x^2+y^2-2
or 2xy=-2
or xy=-1.....sufficient
Ans option D