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finance: Master | Next Rank: 500 Posts; Posts: 150; Joined: Tue Mar 08, 2011 4:38 am; Thanked: 5 times

by finance » Sun Jul 31, 2011 2:09 pm

Is xy positive?

1) (x-y)^2=8
2) (x+y)^2=10

Source: Beat The GMAT — Data Sufficiency | Sun Jul 31, 2011 2:09 pm

edge: Senior | Next Rank: 100 Posts; Posts: 49; Joined: Sun Jun 26, 2011 5:45 pm; Thanked: 2 times

by edge » Sun Jul 31, 2011 2:56 pm

The statements are obviously insufficient by themselves.
Expanding them and subtracting St1 from St2, you get xy = 1/2 > 0.

Hence, C.

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