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

It is currently 22 Sep 2014, 16:33

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

Is x^2 equal to xy? (1) x^2-y^2 = (x + 5)(y - 5) (2) x = y

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
User avatar
Joined: 09 Oct 2005
Posts: 728
Location: Madrid
Followers: 3

Kudos [?]: 11 [0], given: 0

GMAT Tests User
Is x^2 equal to xy? (1) x^2-y^2 = (x + 5)(y - 5) (2) x = y [#permalink] New post 09 Feb 2006, 06:09
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Is x^2 equal to xy?
(1) x^2-y^2 = (x + 5)(y - 5)
(2) x = y
edited sorry for a typo
_________________

IE IMBA 2010


Last edited by Yurik79 on 09 Feb 2006, 06:26, edited 1 time in total.
Director
Director
User avatar
Joined: 05 Feb 2006
Posts: 904
Followers: 1

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

GMAT Tests User
 [#permalink] New post 09 Feb 2006, 06:17
B..... (i believe there is a trick, too easy :) )
Manager
Manager
User avatar
Joined: 01 Feb 2006
Posts: 102
Followers: 1

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

 [#permalink] New post 09 Feb 2006, 07:01
x^2-y^2 = (x + y)(x - y)
x^2-y^2 = (x + 5)(y - 5)
therefore y=5 and x=y; Statement 1 is sufficient

Statement 2 is also sufficient

Answer: D
Director
Director
User avatar
Joined: 05 Feb 2006
Posts: 904
Followers: 1

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

GMAT Tests User
 [#permalink] New post 09 Feb 2006, 07:08
trublu wrote:
x^2-y^2 = (x + y)(x - y)
x^2-y^2 = (x + 5)(y - 5)
therefore y=5 and x=y; Statement 1 is sufficient

Statement 2 is also sufficient

Answer: D


But you cannot determine that x=y from the first statement....
you get x^2-25=x^2-25, where x can be any number....

Second statement gives us the straight answer.....
Manager
Manager
avatar
Joined: 04 Jan 2006
Posts: 58
Followers: 1

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

 [#permalink] New post 09 Feb 2006, 09:19
Hey SimaQ, how did you get that x^2-25 = X^-25?

What's the OA?

If you expand the 1st statement:

x^2 - y^2 = xy - 5x +5y -25
so x^2 = xy -5x +5y -25 +y^2

So Can't we make sure that x^2 is not equal to xy??
Intern
Intern
avatar
Joined: 24 Jan 2006
Posts: 10
Followers: 0

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

 [#permalink] New post 09 Feb 2006, 09:35
if you plug in y=5,

you get x^2 = 25

and that case, x = + or - 5.

therefore you can't solve it with A.

is that right?
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5097
Location: Singapore
Followers: 19

Kudos [?]: 145 [0], given: 0

GMAT Tests User
 [#permalink] New post 09 Feb 2006, 17:37
x^2 = xy
x^2 - xy = 0
x(x-y) = 0
x = 0 or x=y

So x^2 is equal to xy when x is 0 or x is y.

Statement 2 gives us the second condition. So we now need to evaluate statement 1.

x^2-y^2 = (x + 5)(y - 5)
x^2 - y^2 = xy -5x + 5y - 25
x^2 = y^2 + 5 (y - 5 - x)
x^2 = y^2 only when y-x = 5 which we do not know if this is so.

So statement 1 is insufficient.

Ans B
Director
Director
User avatar
Joined: 09 Oct 2005
Posts: 728
Location: Madrid
Followers: 3

Kudos [?]: 11 [0], given: 0

GMAT Tests User
 [#permalink] New post 10 Feb 2006, 08:49
good job guys OA is B
_________________

IE IMBA 2010

Senior Manager
Senior Manager
avatar
Joined: 05 Jan 2006
Posts: 383
Followers: 1

Kudos [?]: 17 [0], given: 0

GMAT Tests User
 [#permalink] New post 10 Feb 2006, 09:00
ywilfred wrote:
x^2-y^2 = (x + 5)(y - 5)
x^2 - y^2 = xy -5x + 5y - 25
x^2 = y^2 + 5 (y - 5 - x)
x^2 = y^2 only when y-x = 5 which we do not know if this is so.
Ans B


Statement 2 is sufficient but I relly could not evalute statement 1!

ywilfred
x^2 - y^2 = xy -5x + 5y - 25
x^2 = y^2 + 5 (y - 5 - x) +xy

so analysis fails there!

Statement 1 si true for x=y=+5 or x=y=-5

But I can not say for sure that these are the only values which satisfy this equation!

And I can not come up with any values which justify this equation except above one!

Anyone has mathemitical proof why statement 1 will be sufficient or not!

What is OA/OE
Manager
Manager
User avatar
Joined: 08 Feb 2006
Posts: 128
Followers: 1

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

Re: DS from DS 1000 [#permalink] New post 11 Feb 2006, 18:43
Yurik79 wrote:
Is x^2 equal to xy?
(1) x^2-y^2 = (x + 5)(y - 5)
(2) x = y
edited sorry for a typo


So is the 1st statement not sufficient because x and y can be 5 or -5?
:moped
Re: DS from DS 1000   [#permalink] 11 Feb 2006, 18:43
    Similar topics Author Replies Last post
Similar
Topics:
Is x^2 equal to xy? (1) x^2 y^2 = (x + 5)(y - 5) (2) x = y Nihit 5 21 Oct 2008, 08:41
Is x^2 equal to xy? (1) x2 y2 = (x + 5)(y - 5) (2) x = y prasannar 5 20 May 2008, 23:44
Is X^2 equal to xy? I. x^2 - y^2 = (x+5)(y-5) II. x=y zhenmaster 5 16 Apr 2008, 09:27
Experts publish their posts in the topic Is x^2 equal to xy? (1) x^2 y^2 = (x + 5)(y - 5) (2) x = y Skewed 5 26 Nov 2007, 10:50
Is x^2 equal to xy? 1) x^2 - y^2 = (x+5)(y-5) 2) x=y jjhko 10 26 Feb 2007, 16:38
Display posts from previous: Sort by

Is x^2 equal to xy? (1) x^2-y^2 = (x + 5)(y - 5) (2) 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®.