Welcome! Check out our free B-School Guides to learn how you compare with other applicants.
Login or Register
 

Scoretop No. 4 - Q 15 - Squares

This topic has 1 expert reply and 2 member replies
Bookmark
Previous Topic Next Topic
akay Rising GMAT Star Default Avatar
Joined
06 May 2007
Posted:
53 messages
Scoretop No. 4 - Q 15 - Squares Post Sun Aug 26, 2007 7:19 am
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    Seems easy...but

    Is x^2 + y^2 > 6

    (1) (x+y)^2 > 6
    (2) xy = 2

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    beny Really wants to Beat The GMAT! Default Avatar
    Joined
    20 Jul 2007
    Posted:
    214 messages
    Thanked:
    2 times
    Post Sun Aug 26, 2007 7:27 am
    Taking the two together, all you know is that x^2+y^2>2.

    Therefore, I'd guess E.

    scholardream Rising GMAT Star Default Avatar
    Joined
    06 May 2011
    Posted:
    83 messages
    Thanked:
    5 times
    Target GMAT Score:
    750
    GMAT Score:
    610
    Post Tue May 01, 2012 5:55 pm
    My answer is E
    1. (x+y)^2 = x^2 + y^2 + 2xy > 6. We can't determine the value of 2xy -> Not sufficient
    2. xy = 2 . x=1, y=2 -> x^2+y^2 < 6 buy x=1/6, y=6 absolutely has bigger value -> Not sufficient
    1&2. x^2 + y^2 > 2 but it doesn't mean x^2+y^2 > 6 or <6 -> Not sufficient

    GMAT/MBA Expert

    Anurag@Gurome GMAT Instructor
    Joined
    02 Apr 2010
    Posted:
    3835 messages
    Followed by:
    465 members
    Thanked:
    1747 times
    GMAT Score:
    770
    Post Tue May 01, 2012 11:48 pm
    akay wrote:
    Seems easy...but

    Is x^2 + y^2 > 6

    (1) (x+y)^2 > 6
    (2) xy = 2
    (1) (x + y)² > 6 implies x² + y² + 2xy > 6
    If x² + y² = 5 and 2xy = 3, then x² + y² < 6
    If x² + y² = 10 and 2xy = 3, then x² + y² > 6
    No definite answer; NOT sufficient.

    (2) xy = 2
    If x = y = √2, then x² + y² = 4 < 6
    If x = 10, y = 1/5, then x² + y² = 100 + 1/25 > 6
    No definite answer; NOT sufficient.

    Combining (1) and (2), x² + y² + 2xy > 6
    x² + y² + 2(2) > 6
    x² + y² + 4 > 6
    x² + y² > 2
    If x² + y² = 5, then x² + y² < 6
    If x² + y² = 10 , then x² + y² > 6
    No definite answer; NOT sufficient.

    The correct answer is E.

    _________________
    Anurag Mairal, Ph.D., MBA
    GMAT Expert, Admissions and Career Guidance
    Gurome, Inc.
    1-800-566-4043 (USA)

    Join Our Facebook Groups
    GMAT with Gurome
    https://www.facebook.com/groups/272466352793633/
    Admissions with Gurome
    https://www.facebook.com/groups/461459690536574/
    Career Advising with Gurome
    https://www.facebook.com/groups/360435787349781/

    Best Conversation Starters
    1 varun289 42 topics
    2 greenwich 25 topics
    3 guerrero 20 topics
    4 sana.noor 19 topics
    5 killerdrummer 19 topics
    See More Top Beat The GMAT Members...

    Most Active Experts
    1 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

    		 196 posts
    2 image description GMATGuruNY

    The Princeton Review Teacher

    		 143 posts
    3 image description Anju@Gurome

    Gurome

    		 121 posts
    4 image description Jim@StratusPrep

    Stratus Prep

    		 86 posts
    5 image description David@VeritasPrep

    Veritas Prep

    		 41 posts
    See More Top Beat The GMAT Experts