GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 18 Dec 2018, 17:32

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.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
  • Happy Christmas 20% Sale! Math Revolution All-In-One Products!

     December 20, 2018

     December 20, 2018

     10:00 PM PST

     11:00 PM PST

    This is the most inexpensive and attractive price in the market. Get the course now!
  • Key Strategies to Master GMAT SC

     December 22, 2018

     December 22, 2018

     07:00 AM PST

     09:00 AM PST

    Attend this webinar to learn how to leverage Meaning and Logic to solve the most challenging Sentence Correction Questions.

Is k^2 + k – 2 > 0?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 51280
Is k^2 + k – 2 > 0?  [#permalink]

Show Tags

New post 29 Oct 2017, 01:03
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

66% (01:57) correct 34% (01:24) wrong based on 76 sessions

HideShow timer Statistics

Manager
Manager
avatar
B
Joined: 21 Jun 2014
Posts: 62
Re: Is k^2 + k – 2 > 0?  [#permalink]

Show Tags

New post 29 Oct 2017, 02:30
For expression to be positive Either K > 1 or K < -2
Option C

Sent from my Moto G (5) Plus using GMAT Club Forum mobile app
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7112
Re: Is k^2 + k – 2 > 0?  [#permalink]

Show Tags

New post 29 Oct 2017, 03:06
1
Bunuel wrote:
Is k^2 + k – 2 > 0?

(1) k < 1
(2) k > –1



Hi...

Let's simplify the equation

\(k^2+k-2>0.........k^2+2k-k-2>0......k(k+2)-1(k+2)>0.....(k+2)(k-1)>0\)..
So both k+2 and k-1 should be of same SIGN..
So a)k between -2 and 1 will give us and NO
b) K<-2 and k>1 will give us and YES

Let's see the statements..
1) k<1...
It will give us falling in both above ranges, so ans can be yes or no
Insufficient
2) k>-1
Same as above
K=0 will give us no
K=5 will give YES
Insufficient

Combined
-1<k<1
This range falls within (a) above
ANS is always NO
Sufficient

C
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Intern
Intern
avatar
B
Joined: 01 Nov 2017
Posts: 29
Re: Is k^2 + k – 2 > 0?  [#permalink]

Show Tags

New post 28 Jun 2018, 08:42
chetan2u wrote:
Bunuel wrote:
Is k^2 + k – 2 > 0?

(1) k < 1
(2) k > –1



Hi...

Let's simplify the equation

\(k^2+k-2>0.........k^2+2k-k-2>0......k(k+2)-1(k+2)>0.....(k+2)(k-1)>0\)..
So both k+2 and k-1 should be of same SIGN..
So a)k between -2 and 1 will give us and NO
b) K<-2 and k>1 will give us and YES

Let's see the statements..
1) k<1...
It will give us falling in both above ranges, so ans can be yes or no
Insufficient
2) k>-1
Same as above
K=0 will give us no
K=5 will give YES
Insufficient

Combined
-1<k<1
This range falls within (a) above
ANS is always NO
Sufficient

C


I don't understand this. Doesn't the formula simplify to the following
1) k^2 + k - 2 > 0
2) k^2 + k > 2
3) k(k+1) > 2
4) k > 2 and k > 1 => So K must be greater than 1 to be more than 0
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7112
Re: Is k^2 + k – 2 > 0?  [#permalink]

Show Tags

New post 28 Jun 2018, 09:16
surfingpirate wrote:
chetan2u wrote:
Bunuel wrote:
Is k^2 + k – 2 > 0?

(1) k < 1
(2) k > –1



Hi...

Let's simplify the equation

\(k^2+k-2>0.........k^2+2k-k-2>0......k(k+2)-1(k+2)>0.....(k+2)(k-1)>0\)..
So both k+2 and k-1 should be of same SIGN..
So a)k between -2 and 1 will give us and NO
b) K<-2 and k>1 will give us and YES

Let's see the statements..
1) k<1...
It will give us falling in both above ranges, so ans can be yes or no
Insufficient
2) k>-1
Same as above
K=0 will give us no
K=5 will give YES
Insufficient

Combined
-1<k<1
This range falls within (a) above
ANS is always NO
Sufficient

C


I don't understand this. Doesn't the formula simplify to the following
1) k^2 + k - 2 > 0
2) k^2 + k > 2
3) k(k+1) > 2
4) k > 2 and k > 1 => So K must be greater than 1 to be more than 0


By doing this you are missing out on the negative values...
It is not mentioned that k is positive..

For example if k =-3...
K(k+1)>2...
-3(-3+1)=-3*-2=6>2
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Intern
Intern
avatar
B
Joined: 01 Nov 2017
Posts: 29
Re: Is k^2 + k – 2 > 0?  [#permalink]

Show Tags

New post 28 Jun 2018, 11:57
C[/quote]

I don't understand this. Doesn't the formula simplify to the following
1) k^2 + k - 2 > 0
2) k^2 + k > 2
3) k(k+1) > 2
4) k > 2 and k > 1 => So K must be greater than 1 to be more than 0[/quote]

By doing this you are missing out on the negative values...
It is not mentioned that k is positive..

For example if k =-3...
K(k+1)>2...
-3(-3+1)=-3*-2=6>2[/quote]
I see. I tested the negative case so ending up figuring that out. How would you represent the negative instance algebraically? Like k(k+1) > 2 (positive) and k(k+1) < -2 (negative)?
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7112
Re: Is k^2 + k – 2 > 0?  [#permalink]

Show Tags

New post 28 Jun 2018, 21:39
surfingpirate wrote:
C

I don't understand this. Doesn't the formula simplify to the following
1) k^2 + k - 2 > 0
2) k^2 + k > 2
3) k(k+1) > 2
4) k > 2 and k > 1 => So K must be greater than 1 to be more than 0
Quote:
By doing this you are missing out on the negative values...
It is not mentioned that k is positive..

For example if k =-3...
K(k+1)>2...
-3(-3+1)=-3*-2=6>2

I see. I tested the negative case so ending up figuring that out. How would you represent the negative instance algebraically? Like k(k+1) > 2 (positive) and k(k+1) < -2 (negative)?


hi..

you are not taking k(k+1)<-2..

you are working on the same equation..
k(k+1)>2..
but here k can take both negative values and positive values...

if k>0, k will have to be greater than 1... so k>1 fulfills the criteria
if k<0, k will have to be less than -2.... so k<-2 also fulfills the criteria
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

GMAT Club Bot
Re: Is k^2 + k – 2 > 0? &nbs [#permalink] 28 Jun 2018, 21:39
Display posts from previous: Sort by

Is k^2 + k – 2 > 0?

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.