Find all School-related info fast with the new School-Specific MBA Forum

It is currently 28 May 2015, 22:37

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Is |x| < 1

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Expert Post
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 5573
Location: Pune, India
Followers: 1374

Kudos [?]: 7006 [0], given: 181

Re: Is |x| < 1 [#permalink] New post 02 Feb 2014, 20:15
Expert's post
jlgdr wrote:
Bunuel wrote:
PiyushK wrote:
For second option I tried to solve it with handy trick.
x^2(x-1)<0

critical points on number line --(+)---0--(-)--1---(+)-- as equation is < 0 trick suggest to pick range between 0-1, this trick mostly worked in all cases even in option 1. But in option 2 it is not working.

You can refer trick on link : inequalities-trick-91482.html#p804990

I am not sure where I am making mistake with this trick.


The squared term, x^2, should be omitted because it's always positive and thus doesn't affect the sign of the left side.


Ahhh now I get it, that's awesome thanks. Still I don't quite know what's wrong with including x^2 in the key points, I know it will give you a different valid range but I would like to understando the logic behind it.

Cheers
J


First understand why we have transition points at all - at the transition point, the sign of one factor changes from positive to negative (starting from right to left). That reverses the sign of the entire inequality. Therefore, we plot the number line with the transition points and make that wave to give different signs to adjoining regions.
Detailed explanation of transition points: http://www.veritasprep.com/blog/2012/06 ... e-factors/

Now what happens when you have x^2? Does x^2 change sign? No, it is ALWAYS positive (or 0). It never becomes negative and hence never reverses the sign of the inequality.
Detailed explanation of even powers: http://www.veritasprep.com/blog/2012/07 ... s-part-ii/
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Veritas Prep GMAT Discount CodesKnewton GMAT Discount CodesKaplan GMAT Prep Discount Codes
Manager
Manager
User avatar
Affiliations: CrackVerbal
Joined: 03 Oct 2013
Posts: 219
Location: India
GMAT 1: 780 Q51 V46
Followers: 30

Kudos [?]: 115 [0], given: 3

Re: Is |x| < 1 [#permalink] New post 02 Feb 2014, 22:19
gmatblues wrote:
Is |x| < 1

(1) x^5 > x^3
(2) x^2 > x^3


Statement I is insufficient:

x = 2 (NO), x = -0.5 (YES)

Statement II is insufficient:

x = 0.5 (NO), x = -3 (YES)

Combining is sufficient:
X has to be a negative fraction as x cannot be a positive number or negative number less than -1.

Hence answer is C
_________________

www.gmat.crackverbal.com

For more info on GMAT and MBA, follow us on @AskCrackVerbal

Re: Is |x| < 1   [#permalink] 02 Feb 2014, 22:19

Go to page   Previous    1   2   [ 22 posts ] 

    Similar topics Author Replies Last post
Similar
Topics:
Is |x-1| < 1? Revenge2013 0 03 Jul 2013, 13:16
Experts publish their posts in the topic Is |x| < 1? Aximili85 4 29 Aug 2012, 09:11
8 Experts publish their posts in the topic Is |x-1| < 1? devinawilliam83 18 12 Feb 2012, 20:49
16 Experts publish their posts in the topic Is |x|<1 ? msand 11 31 Dec 2009, 07:24
Experts publish their posts in the topic Is |x|<1? mosquitojoyride 6 23 Sep 2009, 16:26
Display posts from previous: Sort by

Is |x| < 1

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.