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

It is currently 15 Sep 2014, 01:47

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

m22#3

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 20 Feb 2008
Posts: 296
Location: Bangalore, India
Schools: R1:Cornell, Yale, NYU. R2: Haas, MIT, Ross
Followers: 4

Kudos [?]: 27 [1] , given: 0

GMAT Tests User
m22#3 [#permalink] New post 26 Nov 2008, 18:54
1
This post received
KUDOS
2
This post was
BOOKMARKED
What is the value of x ?

1. x^4 = |x|
2. x^2 \gt x

[Reveal] Spoiler: OA
C

Source: GMAT Club Tests - hardest GMAT questions
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesVeritas Prep GMAT Discount Codes
2 KUDOS received
CEO
CEO
User avatar
Joined: 29 Aug 2007
Posts: 2501
Followers: 53

Kudos [?]: 505 [2] , given: 19

GMAT Tests User
Re: m22#3 [#permalink] New post 26 Nov 2008, 20:49
2
This post received
KUDOS
ventivish wrote:
What is the value of x ?

1. x^4 = |x|
2. x^2 \gt x


1: x = -1 or 0 or 1.

i. if x is +ve,
x^4 = x
x^4 - x = 0
x (x^3 - 1) = 0
x = 0, and x^3 = 1 or x = 1.

ii: if x is -ve,
x^4 = -x
x^4 + x = 0
x (x^3 + 1) = 0
x = 0, and x^3 = -1 or x = -1.
so not suff...


2: x could be anything other than 0 and a +ve fraction.

x^2 > x
x^2 - x > 0
x (x-1) > 0
if x is a +ve (x-1) is also a +ve.
i: x > 0 .......... not possible.

ii: x - 1 > 0
x >1 ............... possible.
so x > 1.

if x is a -ve (x-1) is also a -ve.
i: x < 0 .............. possible.

ii: x < 1 ............... not possible.
so x <0.

1&2: x has to be -1.
so C.
_________________

Verbal: new-to-the-verbal-forum-please-read-this-first-77546.html
Math: new-to-the-math-forum-please-read-this-first-77764.html
Gmat: everything-you-need-to-prepare-for-the-gmat-revised-77983.html


GT

Intern
Intern
avatar
Joined: 15 Nov 2009
Posts: 31
Location: Moscow, Russia
Followers: 0

Kudos [?]: 12 [0], given: 0

Re: m22#3 [#permalink] New post 30 Dec 2009, 05:56
The graphs of y=x^4 and y=|x| 1ntersect each other at three points (-1,1), (0,0) and (1,1), then A is wrong. Any x<0 or x>1 satisfies the inequality x^2>x, then B is wrong.
Both statements together uniquely determine the value x=-1, so C is the answer.

Last edited by nvgroshar on 31 Dec 2009, 14:21, edited 1 time in total.
Manager
Manager
avatar
Joined: 04 Dec 2009
Posts: 72
Location: INDIA
Followers: 2

Kudos [?]: 9 [0], given: 4

Re: m22#3 [#permalink] New post 30 Dec 2009, 20:01
ANS:E from both statement we can conclude only x>1 not a single value.
_________________

MBA (Mind , Body and Attitude )

Intern
Intern
avatar
Joined: 03 Aug 2009
Posts: 1
Followers: 0

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

Re: m22#3 [#permalink] New post 30 Dec 2009, 21:52
It should be C. I thought it E though :shock:
Manager
Manager
avatar
Joined: 20 Oct 2009
Posts: 113
Schools: MIT LGO (Admitted), Harvard (Admitted))
Followers: 7

Kudos [?]: 19 [0], given: 0

GMAT ToolKit User
Re: m22#3 [#permalink] New post 01 Jan 2010, 06:29
1 is not sufficient - x could be 0 or 1, -1
2 X^2>X which means x(x-1)>0 x>1 or x<0

Combine 1 and 2, x=-1
Answer is C
_________________

Dream the impossible and do the incredible.

Live. Love. Laugh.

1 KUDOS received
Manager
Manager
avatar
Joined: 05 Dec 2009
Posts: 127
Followers: 2

Kudos [?]: 76 [1] , given: 0

Re: m22#3 [#permalink] New post 13 Mar 2010, 16:12
1
This post received
KUDOS
When combine both the stmt, we get x = -1, so IMO Ans should be C.
Senior Manager
Senior Manager
User avatar
Joined: 13 Dec 2009
Posts: 264
Followers: 10

Kudos [?]: 106 [0], given: 13

GMAT Tests User Reviews Badge
Re: m22#3 [#permalink] New post 19 Mar 2010, 07:13
ventivish wrote:
What is the value of x ?

1. x^4 = |x|
2. x^2 \gt x

[Reveal] Spoiler: OA
C

Source: GMAT Club Tests - hardest GMAT questions


stmt1L x^4 = x or x^4 = -x
x(x^3-1)=0 or x(x^3+1) =0
so x = 0, -1,1

stmt2: x^2 > x => x(x-1)>0 insuff
combine both. x <>0 or 1 so x is -1
hence c is the answer
_________________

My debrief: done-and-dusted-730-q49-v40

Intern
Intern
User avatar
Status: "You never fail until you stop trying." ~Albert Einstein~
Joined: 16 May 2010
Posts: 31
Followers: 0

Kudos [?]: 4 [0], given: 7

Re: m22#3 [#permalink] New post 06 Jan 2011, 08:39
What is the value of x ?

1. x^4 = |x|

X can equal 1 or -1 or 0 (IS)

2. x^2 > x

x(x-1)>0 (IS)

Both: You can conclude that X is -1 using st.2 to validate it.
1 KUDOS received
Intern
Intern
avatar
Joined: 30 Jul 2010
Posts: 6
Followers: 0

Kudos [?]: 2 [1] , given: 0

Re: m22#3 [#permalink] New post 06 Jan 2011, 09:39
1
This post received
KUDOS
C

From option A, x can be 0 or 1 or -1.
From option B , x can be any negative integer. And it can be any negative fraction value.

Using both we can deduce x value as -1.

Hence the option is c.
Manager
Manager
User avatar
Joined: 01 Nov 2010
Posts: 194
Location: India
Concentration: Technology, Marketing
GMAT Date: 08-27-2012
GPA: 3.8
WE: Marketing (Manufacturing)
Followers: 5

Kudos [?]: 20 [0], given: 29

GMAT Tests User
Re: m22#3 [#permalink] New post 06 Jan 2011, 09:42
x= -1,
excellent explanation were given above.
_________________

kudos me if you like my post.

Attitude determine everything.
all the best and God bless you.

Senior Manager
Senior Manager
avatar
Joined: 19 Oct 2010
Posts: 274
Location: India
GMAT 1: 560 Q36 V31
GPA: 3
Followers: 6

Kudos [?]: 33 [0], given: 27

GMAT Tests User
Re: m22#3 [#permalink] New post 18 Feb 2011, 00:24
I concur with the OA.

Stmt 1 tells you it is +1 or -1
Stmt 2 tells you it is an integer

Combining the two stmts you can tell that the only possible fit is -1. Therefore, it is C.
_________________

petrifiedbutstanding

Director
Director
avatar
Joined: 01 Feb 2011
Posts: 770
Followers: 14

Kudos [?]: 82 [0], given: 42

GMAT Tests User
Re: m22#3 [#permalink] New post 14 Apr 2011, 17:05
1. Not sufficient
When x is +ve x = 1
When x is -ve x = -1

2. Not sufficient
x<0 or x>1

together we have x = -1. Sufficient.

Answer is C.
Manager
Manager
avatar
Joined: 14 Feb 2011
Posts: 198
Followers: 4

Kudos [?]: 61 [0], given: 3

GMAT Tests User
Re: m22#3 [#permalink] New post 14 Apr 2011, 21:49
ventivish wrote:
What is the value of x ?

1. x^4 = |x|
2. x^2 \gt x

[Reveal] Spoiler: OA
C

Source: GMAT Club Tests - hardest GMAT questions


This one is interesting as the answer is different if you do not know that its a GMAT question.

From statement 1, on squaring both sides we get x^8 = x^2
or x^2*(x^6-1) = 0

so, x = 0 or x^6 = 1.

Now x^6 = 1 has six roots and the six sixth roots of unity are ±1, and (±1 ± i√3)/2.

My confusion arose because i considered the complex roots as well and hence my initial reaction was that answer is E.

I guess on GMAT you can go along with only real roots and in that case, answer is indeed C.
Expert Post
2 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23538
Followers: 3482

Kudos [?]: 26116 [2] , given: 2705

Re: m22#3 [#permalink] New post 10 Jan 2013, 05:03
2
This post received
KUDOS
Expert's post
ventivish wrote:
What is the value of x ?

1. x^4 = |x|
2. x^2 \gt x

[Reveal] Spoiler: OA
C

Source: GMAT Club Tests - hardest GMAT questions


What is the value of x ?

(1) x^4 = |x|. This statement implies that x=-1, x=0, or x=1. Not sufficient.

(2) x^2> x. Rearrange and factor out x to get x(x-1)>0. The roots are x=0 and x=1, ">" sign means that the given inequality holds true for: x<0 and x>1. Not sufficient.

(1)+(2) The only value of x from (1) which is in the range from (2) is x=-1. Sufficient.

Answer: C.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Intern
Intern
avatar
Joined: 14 Jul 2012
Posts: 15
Location: United States
Concentration: General Management, International Business
GPA: 3.3
WE: Information Technology (Computer Software)
Followers: 0

Kudos [?]: 5 [0], given: 8

Re: m22#3 [#permalink] New post 11 Jan 2013, 00:14
Answer C (by taking option 1+ 2).
Director
Director
avatar
Status: Gonna rock this time!!!
Joined: 22 Jul 2012
Posts: 550
Location: India
GMAT 1: 640 Q43 V34
GMAT 2: 630 Q47 V29
WE: Information Technology (Computer Software)
Followers: 2

Kudos [?]: 28 [0], given: 562

GMAT Tests User
Re: m22#3 [#permalink] New post 21 Feb 2013, 06:08
Bunuel wrote:
ventivish wrote:
What is the value of x ?

1. x^4 = |x|
2. x^2 \gt x

[Reveal] Spoiler: OA
C

Source: GMAT Club Tests - hardest GMAT questions


What is the value of x ?

(1) x^4 = |x|. This statement implies that x=-1, x=0, or x=1. Not sufficient.

(2) x^2> x. Rearrange and factor out x to get x(x-1)>0. The roots are x=0 and x=1, ">" sign means that the given inequality holds true for: x<0 and x>1. Not sufficient.

(1)+(2) The only value of x from (1) which is in the range from (2) is x=-1. Sufficient.

Answer: C.



Bunuel/Karishma
I dont understand the following:

The roots are x=0 and x=1, ">" sign means that the given inequality holds true for: x<0 and x>1.

shouldn't x(x-1)>0 mean that x>0 or (x-1)>0 ?
Please explain why it means x<0 ?
_________________

hope is a good thing, maybe the best of things. And no good thing ever dies.

Who says you need a 700 ?Check this out : http://gmatclub.com/forum/who-says-you-need-a-149706.html#p1201595

My GMAT Journey : end-of-my-gmat-journey-149328.html#p1197992

Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23538
Followers: 3482

Kudos [?]: 26116 [0], given: 2705

Re: m22#3 [#permalink] New post 21 Feb 2013, 06:19
Expert's post
Sachin9 wrote:
Bunuel wrote:
ventivish wrote:
What is the value of x ?

1. x^4 = |x|
2. x^2 \gt x

[Reveal] Spoiler: OA
C

Source: GMAT Club Tests - hardest GMAT questions


What is the value of x ?

(1) x^4 = |x|. This statement implies that x=-1, x=0, or x=1. Not sufficient.

(2) x^2> x. Rearrange and factor out x to get x(x-1)>0. The roots are x=0 and x=1, ">" sign means that the given inequality holds true for: x<0 and x>1. Not sufficient.

(1)+(2) The only value of x from (1) which is in the range from (2) is x=-1. Sufficient.

Answer: C.



Bunuel/Karishma
I dont understand the following:

The roots are x=0 and x=1, ">" sign means that the given inequality holds true for: x<0 and x>1.

shouldn't x(x-1)>0 mean that x>0 or (x-1)>0 ?
Please explain why it means x<0 ?


Check here:
x2-4x-94661.html#p731476,
inequalities-trick-91482.html,
everything-is-less-than-zero-108884.html?hilit=extreme#p868863,
xy-plane-71492.html?hilit=solving%20quadratic#p841486
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
User avatar
Joined: 28 Apr 2013
Posts: 173
Location: India
GPA: 4
WE: Medicine and Health (Health Care)
Followers: 0

Kudos [?]: 25 [0], given: 84

Re: m22#3 [#permalink] New post 06 Jan 2014, 05:26
OA-C since neither condition 1 nor 2 satisfies the Q to solve x.

Thanks

:-D
_________________

Thanks for Posting

LEARN TO ANALYSE

+1 kudos if you like

Intern
Intern
avatar
Joined: 03 Jan 2014
Posts: 2
Followers: 0

Kudos [?]: 0 [0], given: 1

Re: m22#3 [#permalink] New post 06 Jan 2014, 23:45
statement 1 , x=-1,0,1 NOT SUFFICIENT STATEMENT 2 Not sufficient as universally true, COMBINING statement1& 2 , we found is true for x=-1 hence ans C
Re: m22#3   [#permalink] 06 Jan 2014, 23:45
Display posts from previous: Sort by

m22#3

  Question banks Downloads My Bookmarks Reviews Important topics  

Go to page    1   2    Next  [ 21 posts ] 

Moderators: Bunuel, WoundedTiger



cron

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®.