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

GMAT prep simple ques

This topic has 2 expert replies and 1 member reply
Bookmark
Previous Topic Next Topic
jkelk Just gettin' started! Default Avatar
Joined
12 Mar 2012
Posted:
24 messages
GMAT prep simple ques Post Wed Mar 14, 2012 10:51 am
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    Hi

    Please help solve the attached.

    Thanks,
    J
    Attachments

    This post contains an attachment. You must be logged in to download/view this file. Please login or register as a user.

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!

    GMAT/MBA Expert

    Anurag@Gurome GMAT Instructor
    Joined
    02 Apr 2010
    Posted:
    3835 messages
    Followed by:
    466 members
    Thanked:
    1749 times
    GMAT Score:
    770
    Post Wed Mar 14, 2012 8:57 pm
    jkelk wrote:
    Hi

    Please help solve the attached.

    Thanks,
    J
    Apply the formula, (a + b)² = a² + b² + 2ab

    [√(9 + √80) + √(9 - √80)]² = [√(9 + √80)]² + [√(9 - √80)]² + 2√(9 + √80)√(9 - √80)
    = 9 + √80 + 9 - √80 + 2(81 - 80)
    = 18 + 2
    = 20

    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/

    jkelk Just gettin' started! Default Avatar
    Joined
    12 Mar 2012
    Posted:
    24 messages
    Post Thu Mar 15, 2012 8:55 am
    Hi Anurag,

    Thanks for replying, could you please explain how you simplified 2√(9 + √80)√(9 - √80)
    I seem to be missing this part.

    Thanks,
    J

    GMAT/MBA Expert

    Anurag@Gurome GMAT Instructor
    Joined
    02 Apr 2010
    Posted:
    3835 messages
    Followed by:
    466 members
    Thanked:
    1749 times
    GMAT Score:
    770
    Post Thu Mar 15, 2012 9:10 pm
    jkelk wrote:
    Hi Anurag,

    Thanks for replying, could you please explain how you simplified 2√(9 + √80)√(9 - √80)
    I seem to be missing this part.

    Thanks,
    J
    Apply the formula, (a + b)(a - b) = a² - b²
    2√(9 + √80)√(9 - √80) = 2√{(9 + √80)(9 - √80)}
    = 2√{9² - (√80)²}
    = 2√(81 - 80)
    = 2√1
    = 2

    I hope it helps.

    _________________
    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/

    Thanked by: jkelk

    Best Conversation Starters
    1 varun289 31 topics
    2 sana.noor 23 topics
    3 killerdrummer 21 topics
    4 Rudy414 19 topics
    5 sanaa.rizwan 14 topics
    See More Top Beat The GMAT Members...

    Most Active Experts
    1 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

    		 199 posts
    2 image description GMATGuruNY

    The Princeton Review Teacher

    		 134 posts
    3 image description Jim@StratusPrep

    Stratus Prep

    		 106 posts
    4 image description Anju@Gurome

    Gurome

    		 47 posts
    5 image description Jon@Admissionado

    Admissionado

    		 39 posts
    See More Top Beat The GMAT Experts