x>y?

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 131
Joined: Tue Aug 05, 2008 3:28 pm
Thanked: 2 times

x>y?

by mariah » Sun Nov 29, 2009 4:37 am
Is x > y?
1) x^2 > y^2
2) y - y^2 > 0

oa E
i agree with oa but i don't agree we explanation..

explanation : From II, we cannot determine if Y is positive or not.

how negative number can satisfy second statement ?... i don't get that ...pls explain

Legendary Member
Posts: 1035
Joined: Wed Aug 27, 2008 10:56 pm
Thanked: 104 times
Followed by:1 members

by scoobydooby » Sun Nov 29, 2009 9:40 am
i guess stmnt 2 is insufficient as it doesnt mention x, so we cant answer the question: is x>y

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Sun Nov 29, 2009 9:55 am
mariah wrote:Is x > y?
1) x^2 > y^2
2) y - y^2 > 0

oa E
i agree with oa but i don't agree we explanation..

explanation : From II, we cannot determine if Y is positive or not.

how negative number can satisfy second statement ?... i don't get that ...pls explain
You're right.
Statement II definitely tells us that y is positive.
y - y^2 > 0 (first add y^2 to both sides)
y>y^2
Since y^2 must be greater than or equal to 0, we now know that y must be greater than or equal to 0 (i.e., y is positive)
Brent Hanneson - Creator of GMATPrepNow.com
Image