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11 Sep 2017, 00:28
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C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
70% (01:37) correct
30%
(02:27)
wrong
based on 53
sessions
History
Date
Time
Result
Not Attempted Yet
What is the value of x^2 – y^2 ?
(1) \(2xy = x + y\)
(2) \(x^2y – xy^2 = 1\)
(1) \(2xy = x + y\)
(2) \(x^2y – xy^2 = 1\)
11 Sep 2017, 01:08
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It's a C ...
Statement 1: not sufficient. We don't know the value of x-y.
Statement 2: not sufficient. We don't know the value of X+y.
Statement 1 and 2. We have the individual values of X+y and x-y.
It gives a value of 1.
Sent from my Lenovo TAB S8-50LC using GMAT Club Forum mobile app
Statement 1: not sufficient. We don't know the value of x-y.
Statement 2: not sufficient. We don't know the value of X+y.
Statement 1 and 2. We have the individual values of X+y and x-y.
It gives a value of 1.
Sent from my Lenovo TAB S8-50LC using GMAT Club Forum mobile app
12 Sep 2017, 09:31
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Stem : x^2 - y^2 = (x+y)(x-y)
S1 : 2xy = x+y Not Sufficient
S2 : x^2y-xy^2 = 1 ---> xy(x-y) = 1.
So both, xy = (x-y) = 1. Again Not sufficient.
S1 + S2 = as xy = 1, x+y = 2xy = 2(1) = 2 ---> x+y = 2
and x-y = 1. So (x+y)(x-y) = 2*1 = 2.
Hence C is the answer
S1 : 2xy = x+y Not Sufficient
S2 : x^2y-xy^2 = 1 ---> xy(x-y) = 1.
So both, xy = (x-y) = 1. Again Not sufficient.
S1 + S2 = as xy = 1, x+y = 2xy = 2(1) = 2 ---> x+y = 2
and x-y = 1. So (x+y)(x-y) = 2*1 = 2.
Hence C is the answer
