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

 It is currently 23 Oct 2018, 23:04

### 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

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

# Is 3x − y + z greater than 2x − y + 2z?

Author Message
TAGS:

### Hide Tags

Manager
Joined: 25 Nov 2011
Posts: 201
Location: India
Concentration: Technology, General Management
GPA: 3.95
WE: Information Technology (Computer Software)
Is 3x − y + z greater than 2x − y + 2z?  [#permalink]

### Show Tags

Updated on: 12 Jun 2013, 03:27
1
00:00

Difficulty:

25% (medium)

Question Stats:

75% (01:26) correct 25% (01:48) wrong based on 66 sessions

### HideShow timer Statistics

Is 3x − y + z greater than 2x − y + 2z?

(1) x is positive.

(2) (x^2)*z is negative.

_________________

-------------------------
-Aravind Chembeti

Originally posted by Chembeti on 25 Feb 2012, 23:50.
Last edited by Bunuel on 12 Jun 2013, 03:27, edited 2 times in total.
Edited the question
Math Expert
Joined: 02 Sep 2009
Posts: 50078
Re: Is 3x − y + z greater than 2x − y + 2z?  [#permalink]

### Show Tags

25 Feb 2012, 23:58
Is 3x − y + z greater than 2x − y + 2z?

Is $$3x-y+z>2x-y+2z$$? --> is $$x>z$$?

(1) x is positive. No info about $$z$$. Not sufficient.

(2) (x^2)*z is negative --> $$(x^2)*z<0$$ --> $$z$$ is negative, but limited info about $$x$$ (we only know that $$x\neq{0}$$). Not sufficient.

(1)+(2) From (1) $$x$$ is positive and from (2) $$z$$ is negative --> $$x>z$$. Sufficient.

_________________
Intern
Joined: 26 Feb 2012
Posts: 2
Re: Is 3x − y + z greater than 2x − y + 2z?  [#permalink]

### Show Tags

26 Feb 2012, 13:59
Bunuel wrote:
Is 3x − y + z greater than 2x − y + 2z?

Is $$3x-y+z>2x-y+2z$$? --> is $$x>z$$?

(1) x is positive. No info about $$z$$. Not sufficient.

(2) x^2*z is negative --> $$x^2*z<0$$ --> $$z$$ is negative, but limited info about $$x$$ (we only know that $$x\neq{0}$$). Not sufficient.

(1)+(2) From (1) $$x$$ is positive and from (2) $$z$$ is negative --> $$x>z$$. Sufficient.

How did you deduce z must be negative?

From exponent rule, $$b^(-n)$$ is $$1/b^n$$. This will always be positive if n is even, regardless of the base. Since $$n = 2z$$, $$x^(2*z)$$ will always be positive, which contradicts the original statement #2. Am I missing something here?
Math Expert
Joined: 02 Sep 2009
Posts: 50078
Re: Is 3x − y + z greater than 2x − y + 2z?  [#permalink]

### Show Tags

26 Feb 2012, 14:04
PlayStation64 wrote:
Bunuel wrote:
Is 3x − y + z greater than 2x − y + 2z?

Is $$3x-y+z>2x-y+2z$$? --> is $$x>z$$?

(1) x is positive. No info about $$z$$. Not sufficient.

(2) x^2*z is negative --> $$x^2*z<0$$ --> $$z$$ is negative, but limited info about $$x$$ (we only know that $$x\neq{0}$$). Not sufficient.

(1)+(2) From (1) $$x$$ is positive and from (2) $$z$$ is negative --> $$x>z$$. Sufficient.

How did you deduce z must be negative?

From exponent rule, $$b^(-n)$$ is $$1/b^n$$. This will always be positive if n is even, regardless of the base. Since $$n = 2z$$, $$x^(2*z)$$ will always be positive, which contradicts the original statement #2. Am I missing something here?

Welcome to GMAT Club.

I think you misunderstood the statement: it's $$(x^2)*z<0$$ not $$x^{(2z)}<0$$: 2 is an exponent and z is a multiple and not that 2z is an exponent.

Hope it's clear.
_________________
Intern
Joined: 26 Feb 2012
Posts: 2
Re: Is 3x − y + z greater than 2x − y + 2z?  [#permalink]

### Show Tags

26 Feb 2012, 14:07
Ahhh! Thanks for the clarification! This changes everything!
Non-Human User
Joined: 09 Sep 2013
Posts: 8546
Re: Is 3x − y + z greater than 2x − y + 2z?  [#permalink]

### Show Tags

24 Nov 2017, 00:35
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Is 3x − y + z greater than 2x − y + 2z? &nbs [#permalink] 24 Nov 2017, 00:35
Display posts from previous: Sort by