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

It is currently 30 Aug 2015, 02:29
GMAT Club Tests

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

what is the value of x y

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Director
Director
User avatar
Joined: 19 Mar 2007
Posts: 524
Followers: 3

Kudos [?]: 10 [0], given: 0

what is the value of x y [#permalink] New post 11 Jun 2007, 06:03
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

what is the value of x – y?

Last edited by nick_sun on 28 Jun 2008, 01:14, edited 1 time in total.
SVP
SVP
User avatar
Joined: 01 May 2006
Posts: 1798
Followers: 10

Kudos [?]: 108 [0], given: 0

 [#permalink] New post 11 Jun 2007, 07:25
(A) for me :)

x-y = ?

From 1
(x^2 – y^2) / (x + y) = 4
<=> (x-y) * (x+y) / (x+y) = 4
<=> x - y = 4

SUFF.

From 2
x + y = 7 >>> we can do nothing with it...

Picking numbers to be sure?
o If x=3 and y = 4, then x-y = -1
o If x=4 and y = 3, then x-y = 1

INSUFF.
Director
Director
User avatar
Joined: 19 Mar 2007
Posts: 524
Followers: 3

Kudos [?]: 10 [0], given: 0

 [#permalink] New post 12 Jun 2007, 11:26
Thanks, Fig! The answer is A. Can't make myself factorize the quadratic equations :lol:
CEO
CEO
User avatar
Joined: 17 May 2007
Posts: 2994
Followers: 59

Kudos [?]: 493 [0], given: 210

 [#permalink] New post 12 Jun 2007, 23:49
Shouldn't the answer be C ?

Otherwise how would u know that x+y not equal to 0 ?

I remember a similar question in one of the challenges.
CEO
CEO
User avatar
Joined: 17 May 2007
Posts: 2994
Followers: 59

Kudos [?]: 493 [0], given: 210

 [#permalink] New post 12 Jun 2007, 23:50
I retract my earlier comment. x and y are positive hence A is indeed sufficient.
SVP
SVP
User avatar
Joined: 01 May 2006
Posts: 1798
Followers: 10

Kudos [?]: 108 [0], given: 0

 [#permalink] New post 12 Jun 2007, 23:56
bsd_lover wrote:
Shouldn't the answer be C ?

Otherwise how would u know that x+y not equal to 0 ?

I remember a similar question in one of the challenges.


x+y must be different from 0 because the equation exists and is stated :)... It's true that in the real GMAT, it will be stated that x+y != 0 to avoid any confusion.

We just have to remove a solution to the equation that does x+y=0 if such a solution exists. :)

Here, we arrive to x-y = 4 and we should keep in mind that the intersection of the 2 lines x-y = 4 and x+y = 0 must be removed.... But for this problem, we do not care it :)
SVP
SVP
User avatar
Joined: 01 May 2006
Posts: 1798
Followers: 10

Kudos [?]: 108 [0], given: 0

 [#permalink] New post 12 Jun 2007, 23:59
bsd_lover wrote:
I retract my earlier comment. x and y are positive hence A is indeed sufficient.


Also yes ;)
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5067
Location: Singapore
Followers: 24

Kudos [?]: 212 [0], given: 0

 [#permalink] New post 13 Jun 2007, 00:03
St1:
(x+y)(x-y)/(x+y) = 4
x-y = 4 --> sufficient.

St2:
x+y = 7, but there are many possible (x,y) solutions each giving different x-y results. --> insufficient.

ans A
Manager
Manager
avatar
Joined: 17 Oct 2006
Posts: 52
Followers: 0

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

 [#permalink] New post 13 Jun 2007, 02:23
my vote is for A too.
Director
Director
User avatar
Joined: 30 Nov 2006
Posts: 591
Location: Kuwait
Followers: 13

Kudos [?]: 190 [0], given: 0

 [#permalink] New post 13 Jun 2007, 06:48
(1) (x^2 – y^2) / (x + y) = 4
------------------------------------
(x^2 - y^2) = (x-y) (x+y)

Thus: (x^2 – y^2) / (x + y) = (x - y) = 4

statement 1 is sufficient


(2) x + y = 7
-----------------
Two variables one equation .. we can conclude nothing about x - y ..

statement 2 is insufficient

ANSWER: A
  [#permalink] 13 Jun 2007, 06:48
Display posts from previous: Sort by

what is the value of x y

  Question banks Downloads My Bookmarks Reviews Important topics  


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®.