• PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • 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
  • 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

Product of slopes

This topic has 1 member reply
maxim730 Senior | Next Rank: 100 Posts Default Avatar
Joined
26 Dec 2006
Posted:
76 messages
Followed by:
2 members

Product of slopes

Post Tue Mar 27, 2007 6:48 pm
THanks in advance for your explanation.
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
Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
jayhawk2001 Community Manager
Joined
28 Jan 2007
Posted:
789 messages
Followed by:
1 members
Upvotes:
30
Top Reply
Post Tue Mar 27, 2007 9:36 pm
Let the equation of the 2 lines l and k be

y = m1 * x + c1
y = m2 * x + c2

1 - Insufficient. Product of x intercepts = +ve.
We know that x intercept is the point at which y = 0

For line l: x = -c1 / m1
For line k: x = -c2 / m2

Product = c1c2 / m1m2 > 0

We can't infer that m1m2 > 0 since it depends on c1c2

2 - insufficient. Y intercept is -ve

For line l: y = c1
For line k: y = c2

Product = c1c2 < 0

We can't infer m1m2 from here

If we combine 1 and 2, we have c1c2 < 0 which implies that m1m2 < 0
(for c1c2/m1m2 > 0)

Hence C

I think I'm missing some datapoint here as I haven't made use of (4,3)
in the question stem...

  • +1 Upvote Post
  • Quote
  • Flag

Best Conversation Starters

1 lheiannie07 116 topics
2 LUANDATO 68 topics
3 swerve 65 topics
4 ardz24 65 topics
5 Roland2rule 64 topics
See More Top Beat The GMAT Members...

Most Active Experts

1 image description Scott@TargetTestPrep

Target Test Prep

198 posts
2 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

181 posts
3 image description Jeff@TargetTestPrep

Target Test Prep

168 posts
4 image description Rich.C@EMPOWERgma...

EMPOWERgmat

134 posts
5 image description GMATGuruNY

The Princeton Review Teacher

119 posts
See More Top Beat The GMAT Experts