GMAT Changed on April 16th - Read about the latest changes here
close

It is currently 26 Apr 2018, 14:05
Search
Register
GMAT Club Tests
Decision Tracker
My Rewards
New posts
Unanswered

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.

Go to My Workbook Learn more
Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar
CLICK HERE TO HIDE/SHOW EVENTS

Is x > 0? 1) x^3+x^2+x<0 2) x^2<1

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
  Sort by Date Sort by Kudos  
Search for:
 
Print view
First unread post
Author Message
TAGS:

Hide Tags
Expert Post
Math Revolution GMAT Instructor
User avatar
D
Joined: 16 Aug 2015
Posts: 5288
GMAT 1: 800 Q59 V59
GPA: 3.82
Premium Member
Top Member of the Month
Is x > 0? 1) x^3+x^2+x<0 2) x^2<1 [#permalink]

Show Tags

New post 06 Nov 2017, 21:51
Expert's post
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

75% (00:47) correct 25% (01:05) wrong based on 48 sessions

HideShow timer Statistics

[GMAT math practice question]

Is \(x > 0\)?

1) \(x^3+x^2+x<0\)
2) \(x^2<1\)
[Reveal] Spoiler: OA

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $79 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Intern
Intern
avatar
B
Joined: 28 Dec 2010
Posts: 49
Re: Is x > 0? 1) x^3+x^2+x<0 2) x^2<1 [#permalink]

Show Tags

New post 06 Nov 2017, 21:56
1. \(x^3 + x^2 + x > 0\)
\(x ( x^2 + x + 1) > 0\)

Here \(x^2 + x + 1 is always > 0\)
So x<0
Sufficient.

2. \(x^2<1\)
\((x+1)(x-1) < 0\)
x>-1 ; x < 1
Insufficient.

A.
_________________

_________________________________________
Please Kudos, if you found this post helpful.

Expert Post
Math Revolution GMAT Instructor
User avatar
D
Joined: 16 Aug 2015
Posts: 5288
GMAT 1: 800 Q59 V59
GPA: 3.82
Premium Member
Top Member of the Month
Re: Is x > 0? 1) x^3+x^2+x<0 2) x^2<1 [#permalink]

Show Tags

New post 09 Nov 2017, 00:42
Expert's post
=>

Forget conventional ways of solving math questions. In DS, VA (Variable Approach) method is the easiest and quickest way to find the answer without actually solving the problem. Remember that equal number of variables and independent equations ensures a solution.

Since we have 1 variable and 0 equation, D is most likely to be the answer.

Conditions 1) x^3+x^2+x<0
x(x^2+x+1)<0 implies x < 0, since x^2+x+1 > 0.
The answer is no.
Since “no” is also an answer according to CMT (Common Mistake Time) 1, this is sufficient.

Condition 2) x^2<1
We have x2-1 < 0 and (x+1)(x-1) < 0.
Thus, you get -1 < x < 1 according to the “between” rule in inequalities.
This is not sufficient.

Therefore, A is the answer.


For cases where we need 1 more equation, such as original conditions with “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations”, we have 1 equation each in both con 1) and con 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. D is most likely to be the answer using con 1) and con 2) separately according to DS definition. Obviously, there may be cases where the answer is A, B, C or E.
Ans: A
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $79 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Re: Is x > 0? 1) x^3+x^2+x<0 2) x^2<1   [#permalink] 09 Nov 2017, 00:42
Print view
First unread post
Display posts from previous: Sort by

Is x > 0? 1) x^3+x^2+x<0 2) x^2<1

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  

Moderators: chetan2u, VeritasPrepKarishma, Bunuel, mikemcgarry, amanvermagmat, gmatbusters

Search for:


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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.

Main navigation

GMAT Resources

Partners

MBA Resources

www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions