If xy > o, does (x-1)(y-1) = 1?
1. x+y = xy
2. x = y
OA says 2 is not sufficient but I think I disagree.
(y-1)(y-1) = 1
y^2 - 2y +1 = 1
Y^2-2y = 0.
y(y-2) = 0.
yes we have 2 answer , y =0 or 2... BUT
plugging back into equation we get (0-1)(0-1) =1 and (2-1)(2-1) =1.
Thus B is sufficient. BTW.. this is from the official quant review so I am rather vary of trying to prove it wrong..
1. x+y = xy
2. x = y
OA says 2 is not sufficient but I think I disagree.
(y-1)(y-1) = 1
y^2 - 2y +1 = 1
Y^2-2y = 0.
y(y-2) = 0.
yes we have 2 answer , y =0 or 2... BUT
plugging back into equation we get (0-1)(0-1) =1 and (2-1)(2-1) =1.
Thus B is sufficient. BTW.. this is from the official quant review so I am rather vary of trying to prove it wrong..
