• NEW! FREE Beat The GMAT Quizzes
    NEW! FREE Beat The GMAT Quizzes
    NEW! FREE Beat The GMAT Quizzes
    Hundreds of Questions Highly Detailed Reporting Expert Explanations TAKE A FREE GMAT QUIZ
  • 7 CATs FREE!
    If you earn 100 Forum Points

    Engage in the Beat The GMAT forums to earn
    100 points for $49 worth of Veritas practice GMATs FREE

    Veritas Prep
    VERITAS PRACTICE GMAT EXAMS
    Earn 10 Points Per Post
    Earn 10 Points Per Thanks
    Earn 10 Points Per Upvote
    REDEEM NOW

algebra- inequalities

This topic has 1 expert reply and 1 member reply

algebra- inequalities

Post
Is y a negative number?
1) y +2 is positive
2) y^2 > 10

please explain the second part (inequality)

  • +1 Upvote Post
  • Quote
  • Flag
Legendary Member
Joined
14 Aug 2012
Posted:
1556 messages
Followed by:
34 members
Upvotes:
448
Target GMAT Score:
750
GMAT Score:
650
Post
To find: y is negative?

Statement 1:

y+2 positive.
Y = -1 , y+2 = -1+2 = 1 YES
Y = 0 , y+2 = 0+2 = 2 NO
INSUFFICIENT

Statement 2:
y^2 > 10
y = -4 ==> y^2 = 16
y = +4 ==> y^2 = 16
INSUFFICIENT

Combining...
for y+2 to be positive.. the negative value of y >= -1.9
for y^2 > 10.. we need y <-3._ oy y>3._
hence, Y is Positive
SUFFICIENT
{C}

_________________
R A H U L

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Post
pritam.ryders wrote:
Is y a negative number?

1) y + 2 is positive
2) y² > 10
Target question: Is y negative?

Statement 1: y + 2 is positive
In other words, y + 2 > 0
Subtract 2 from both sides to get y > -2
From this information, can we determine whether or not y is negative?
No.
Consider these two conflicting cases:
Case a: y = -1, in which case y IS negative
Case b: y = 1, in which case y is NOT negative
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: y² > 10
There are two possible sets of y-values that satisfy this inequality
Case a: y > √10, in which case y is NOT negative
Case b: y < -√10, in which case y IS negative
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
Statement 2 presents us with two possible cases:
Case a: y > √10
Case b: y < -√10

Statement 1 tells us that y > -2. This eliminates case b, since y cannot simultaneously be greater than -2 AND less than -√10 (≈3.2).
This means that it MUST be the case that y > √10, which means y is definitely NOT negative.
Since we can answer the target question with certainty, the combined statements are SUFFICIENT

Answer = C

Cheers,
Brent

_________________
Brent Hanneson – Creator of GMATPrepNow.com
Use our video course along with Beat The GMAT's free 60-Day Study Guide

Sign up for our free Question of the Day emails
And check out all of our free resources

  • +1 Upvote Post
  • Quote
  • Flag
GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!
  • 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
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • The Princeton Review
    FREE GMAT Exam
    Know how you'd score today for $0

    Available with Beat the GMAT members only code

    MORE DETAILS
    The Princeton Review
  • 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

Top First Responders*

1 Jay@ManhattanReview 71 first replies
2 Brent@GMATPrepNow 67 first replies
3 GMATGuruNY 43 first replies
4 Ian Stewart 27 first replies
5 Scott@TargetTestPrep 18 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

Most Active Experts

1 image description Scott@TargetTestPrep

Target Test Prep

221 posts
2 image description Max@Math Revolution

Math Revolution

93 posts
3 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

90 posts
4 image description Jay@ManhattanReview

Manhattan Review

73 posts
5 image description GMATGuruNY

The Princeton Review Teacher

66 posts
See More Top Beat The GMAT Experts