Is x^3 > x^2? (1) x > 0 (2) x^2 > x

Oldest

Best Reply

Author

Message

TAGS:

Intern

Joined: 26 Jul 2010

Posts: 24

Followers: 0

Kudos [?]: 2 [0], given: 8

Is x^3 > x^2? (1) x > 0 (2) x^2 > x [#permalink]

06 May 2012, 19:29

00:00

Question Stats:

51% (01:55) correct

48% (00:08) wrong

based on 1 sessions

Is x^3 > x^2?

(1) x > 0
(2) x^2 > x

[Reveal] Spoiler: OA

Manager

Joined: 17 Sep 2011

Posts: 174

Concentration: Strategy, General Management

GMAT 1: 720 Q48 V40

GPA: 3.18

WE: Sales (Energy and Utilities)

Followers: 10

Kudos [?]: 25 [0], given: 31

Re: Inequalities [#permalink]

06 May 2012, 21:23

pgmat wrote:

Is x^3 > x^2?
1. x > 0
2. x^2 > x

Can some one explain how to solve this?

I hope yo know the basic structure of DS questions? You need to first check the suffecieny of statement 1...then for statement 2....and if neither is insuffecient on its own...then test for suffeciency together etc...

St1: X>0
his means x could be a number like 1/2 (which between 0 and 1) or could be a number like 2 (>1)...
for x=1/2, x^3<x^2 as 1/8<1/4
for x=2, X^3>X^2 as 8>4.
As both cases are possible, statement 1 alone is not suffecient to say if x^3>x^2 or not

St2: this says x^2>x => x(x-1)>0 =>x>1 or x<0 =>x could be numbers like -1/2,-2, 2
for x =-1/2, x^3<x^2
for x= -2, x^3<x^2
for x= 2, X^3>x^2....
hence not suffecient to say ifx^3 is greater thanX^2 or not

St1 and St2 together: X>0 AND (X>1 or X<0)....only numbers satisfying both cases (or in other words only common area for both cases on number line) is for x>1....for all x greater than 1. x^3>x^2...so suffecient to say YES to the question asked.

GMAT Club team member

Joined: 02 Sep 2009

Posts: 11565

Followers: 1796

Kudos [?]: 9571 [0], given: 826

Re: Is x^3 > x^2? (1) x > 0 (2) x^2 > x [#permalink]

06 May 2012, 23:42

Is x^3 > x^2?

Is x^3>x^2? --> since x^2 cannot be negative we can safely reduce by it: is x>1?

(1) x > 0. Not sufficient.
(2) x^2 > x --> x(x-1)>0 --> x<0 or x>1. Not sufficient.

(1)+(2) Intersection of the ranges from (1) and (2) is x>1, so the answer to the question is YES. Sufficient.

Answer: C.

Solving inequalities:
x2-4x-94661.html#p731476
inequalities-trick-91482.html
data-suff-inequalities-109078.html
range-for-variable-x-in-a-given-inequality-109468.html?hilit=extreme#p873535
everything-is-less-than-zero-108884.html?hilit=extreme#p868863

Hope it helps.
_________________

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

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. NEW!!!

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. NEW!!!

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

Find out what's new at GMAT Club - latest features and updates

Intern

Joined: 09 Jun 2012

Posts: 10

Followers: 0

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

Re: Is x^3 > x^2? (1) x > 0 (2) x^2 > x [#permalink]

14 Mar 2013, 03:18

Bunuel wrote:

Is x^3 > x^2?

Is x^3>x^2? --> since x^2 cannot be negative we can safely reduce by it: is x>1?

Hi Bunuel,

In this case, we dont know if x is not equal to zero. Without knowing that can we divide the eqn by x^2 which will also be zero?

Thanks,
Jaisri

GMAT Club team member

Joined: 02 Sep 2009

Posts: 11565

Followers: 1796

Kudos [?]: 9571 [0], given: 826

Re: Is x^3 > x^2? (1) x > 0 (2) x^2 > x [#permalink]

14 Mar 2013, 03:23

Jaisri wrote:

Bunuel wrote:

Is x^3 > x^2?

Is x^3>x^2? --> since x^2 cannot be negative we can safely reduce by it: is x>1?

Hi Bunuel,

In this case, we dont know if x is not equal to zero. Without knowing that can we divide the eqn by x^2 which will also be zero?

Thanks,
Jaisri

If x=0, then x^3>x^2 won't hold true. Or in another way: is x^3>x^2? --> is x^2(x-1)>0? is x>1?
_________________

Intern

Joined: 09 Jun 2012

Posts: 10

Followers: 0

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

Re: Is x^3 > x^2? (1) x > 0 (2) x^2 > x [#permalink]

14 Mar 2013, 04:11

Thanks for your reply! I am getting the bigger picture of how you do things now. Thanks again!

Re: Is x^3 > x^2? (1) x > 0 (2) x^2 > x [#permalink] 14 Mar 2013, 04:11

	Similar topics	Author	Replies	Last post
Similar Topics:	Is X>1? 1) x^3>x 2) x^2>x>0	Professor	9	19 Mar 2006, 16:39
	Is X>3? 1) (x-3)(x-2)(x-1)>0 2) x>1	GK_Gmat	4	04 Jul 2007, 01:30
	Is x>0? 1) x^2+x-2>0 2) x^3<x^2 (A) Statement 1	suntaurian	7	25 Jan 2008, 16:44
	Is x^3 > x^2? (1) x > 0 (2) x^2 > x	skim	1	05 Jun 2009, 20:18
	Is (x-2)^2>x^2 ? 1. x^2>x 2. 1/x>0	gmatpapa	5	05 Jan 2011, 09:21

Is x^3 > x^2? (1) x > 0 (2) x^2 > x

Main navigation

GMAT Resources

Partners

MBA Resources

GMAT ® is a registered trademark of the Graduate Management Admission Council ® (GMAC ®). GMAT Club's website has not been reviewed or endorsed by GMAC.

GMAT Courses

Admissions Consulting

Is x^3 > x^2? (1) x > 0 (2) x^2 > x

Is x^3 > x^2? (1) x > 0 (2) x^2 > x

Main navigation

GMAT Resources

Partners

MBA Resources