• Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • examPAL
    Most awarded test prep in the world
    Now free for 30 days

    Available with Beat the GMAT members only code

    MORE DETAILS
    examPAL
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors

Difficult Math Question #19 - Difficult Alegbra

This topic has 2 member replies
800guy Master | Next Rank: 500 Posts Default Avatar
Joined
27 Jun 2006
Posted:
354 messages
Followed by:
5 members
Upvotes:
11

Difficult Math Question #19 - Difficult Alegbra

Post Fri Sep 22, 2006 10:03 am
OA coming after a few people answer. see image below..
Attachments

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

  • +1 Upvote Post
  • Quote
  • Flag
800guy Master | Next Rank: 500 Posts Default Avatar
Joined
27 Jun 2006
Posted:
354 messages
Followed by:
5 members
Upvotes:
11
Post Tue Sep 26, 2006 5:53 pm
here's the OA:

The method I followed was to reduce the Q to (x^6/ x ) * ( Y/Y)
the eqn An= (x ^ n -1)(1+ x + x^2 + x^3 +.... ) ----------------------------(1)

and the eqn x(1+x(1+x(1+x...))))
which I call Z can be reduced to x( 1+x+x^2+x^3 ..) --------(2)

from (1) and (2) we get An / Z = x^(n-1) / x
therefore for getting answer x^5 (n-1) = 6
therefore n=7

Ans: B

  • +1 Upvote Post
  • Quote
  • Flag
gamemaster Senior | Next Rank: 100 Posts Default Avatar
Joined
03 Sep 2006
Posted:
34 messages
Post Fri Sep 22, 2006 1:05 pm
The expression in the multiple brackets equals eventually:

S = x+x^2+x^3+x^4+x^5

according to the question, An/S = x^5

=> An = x^6+x^7+x^8+x^9+x^10

so its easy to see n = 7

  • +1 Upvote Post
  • Quote
  • Flag

Best Conversation Starters

1 lheiannie07 108 topics
2 ardz24 67 topics
3 Roland2rule 63 topics
4 LUANDATO 52 topics
5 Vincen 51 topics
See More Top Beat The GMAT Members...

Most Active Experts

1 image description GMATGuruNY

The Princeton Review Teacher

150 posts
2 image description Jeff@TargetTestPrep

Target Test Prep

114 posts
3 image description Rich.C@EMPOWERgma...

EMPOWERgmat

105 posts
4 image description Scott@TargetTestPrep

Target Test Prep

101 posts
5 image description Max@Math Revolution

Math Revolution

85 posts
See More Top Beat The GMAT Experts