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

It is currently 20 Oct 2014, 23:35

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

If x<=y and y = (x^2 - y^2)(x-y), then what is the value of

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
2 KUDOS received
VP
VP
User avatar
Joined: 05 Jul 2008
Posts: 1435
Followers: 35

Kudos [?]: 225 [2] , given: 1

If x<=y and y = (x^2 - y^2)(x-y), then what is the value of [#permalink] New post 12 Oct 2008, 12:38
2
This post received
KUDOS
1
This post was
BOOKMARKED
If x\neq{y} and y = \frac{x^2 - y^2}{x-y}, then what is the value of y ?

(1) x+y-3=0
(2) x(y-3)=0

Source: GMAT Club Tests - hardest GMAT questions

Last edited by Bunuel on 07 Nov 2013, 01:13, edited 2 times in total.
Updated
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesGMAT Pill GMAT Discount Codes
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23348
Followers: 3602

Kudos [?]: 28683 [0], given: 2808

Re: If y = \frac {x^2 - y^2}{x-y} ( x \ne y ), then what is the [#permalink] New post 09 Nov 2012, 05:41
Expert's post
icandy wrote:
If y = \frac {x^2 - y^2}{x-y} ( x \ne y ), then what is the value of y ?

1. x + y = 3
2. x - y = 2

[Reveal] Spoiler: OA
D

Source: GMAT Club Tests - hardest GMAT questions

Given is y=x+y meaning x=0

(1) says y=3 and (2) says y=-2

Given answer is D.

Isn't it one of the cardinal rules of GMAT that (1) and (2) do not contradict each other? Am I misinterpreting some thing here? The way I understood is if D were to be the answer for any DS Q, we should get the same value. If we are not getting such same answer, either we are doing some thing wrong or the Q itself is wrong.

Thoughts Fellas.


BELOW IS REVISED QUESTION OF THIS QUESTION:

If x\neq{y} and y = \frac{x^2 - y^2}{x-y}, then what is the value of y ?

y = \frac {x^2 - y^2}{x-y} --> y = \frac {(x - y)(x+y)}{x-y} --> y=x+y --> x=0.

(1) x+y-3=0 --> y=3. Sufficient.
(2) x(y-3)=0 --> since x=0 then y can take ANY value. Not sufficient.

Answer: A.
_________________

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

2 KUDOS received
Intern
Intern
avatar
Joined: 21 Oct 2012
Posts: 13
Followers: 0

Kudos [?]: 27 [2] , given: 16

Re: If y = \frac {x^2 - y^2}{x-y} ( x \ne y ), then what is the [#permalink] New post 09 Nov 2012, 09:43
2
This post received
KUDOS
Answer :D

Since both the options are independently sufficient to answer the question. (Value of y)

Although the value of y is not unique, if we get a solution for y it makes the option valid.
Current Student
avatar
Joined: 12 Dec 2012
Posts: 34
Concentration: Leadership, Social Entrepreneurship
GMAT 1: Q V
GMAT 2: 660 Q48 V33
GMAT 3: 740 Q49 V41
GPA: 3.74
Followers: 2

Kudos [?]: 48 [0], given: 19

Re: If x<=y and y = (x^2 - y^2)(x-y), then what is the value of [#permalink] New post 06 Nov 2013, 07:44
The OA to this question should be edited. I also got A but it said my answer was incorrect. Only realized once I read Bunuel's explanation.

OA still shows D.
Manager
Manager
avatar
Joined: 11 Jan 2011
Posts: 71
GMAT 1: 680 Q44 V39
GMAT 2: 710 Q48 V40
Followers: 0

Kudos [?]: 4 [0], given: 3

GMAT ToolKit User
Re: If x<=y and y = (x^2 - y^2)(x-y), then what is the value of [#permalink] New post 06 Nov 2013, 09:15
Answer: A

Given: Image = \frac{(x+y)(x-y)}{(x-y)}, which simplifies to y = x + y

Asked: What does y equal but is actually asking for x + y

1) Given: x + y = 3 --> insta-sufficient
2) Given: x - y = 2 --> insufficient since it tells us nothing about x + y

Therefore, A.

I'm really not sure why the OA says D....
Current Student
avatar
Joined: 18 May 2013
Posts: 41
Concentration: Real Estate, Finance
GMAT 1: 660 Q V
GPA: 3.73
WE: Analyst (Real Estate)
Followers: 0

Kudos [?]: 4 [0], given: 2

Re: If x<=y and y = (x^2 - y^2)(x-y), then what is the value of [#permalink] New post 06 Nov 2013, 16:41
Answer should be A.
Intern
Intern
avatar
Joined: 04 Aug 2013
Posts: 5
Followers: 0

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

Re: If x<=y and y = (x^2 - y^2)(x-y), then what is the value of [#permalink] New post 06 Nov 2013, 21:10
I think the answer is D

From question y = x+y
1) x+y-3=0 ==> Since y = x+y ==> y-3=0 and y=3
2) x-y = 2 ==> x-(x+y) = 2 ==> x-x-y = 2 ==> -y=2 and y = 2

How X(y-3)=0 is obtained ?

Please help
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23348
Followers: 3602

Kudos [?]: 28683 [0], given: 2808

Re: If x<=y and y = (x^2 - y^2)(x-y), then what is the value of [#permalink] New post 07 Nov 2013, 01:15
Expert's post
mhknair wrote:
I think the answer is D

From question y = x+y
1) x+y-3=0 ==> Since y = x+y ==> y-3=0 and y=3
2) x-y = 2 ==> x-(x+y) = 2 ==> x-x-y = 2 ==> -y=2 and y = 2

How X(y-3)=0 is obtained ?

Please help


The revised version of this question is here: if-x-y-and-y-x-2-y-2-x-y-then-what-is-the-value-of-71567.html#p1141701 and the OA is A.
_________________

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

Re: If x<=y and y = (x^2 - y^2)(x-y), then what is the value of   [#permalink] 07 Nov 2013, 01:15
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic If xy≠0 and x^2*y^2-xy=6, which of the following could be y Baten80 3 16 Jan 2012, 10:26
If xy ≠ 0 and x^2y^2 – xy = 6, which of the following could Jcpenny 3 09 Nov 2008, 19:47
If xy ≠ 0 and x^2y^2 xy = 6, which of the following apollo168 3 22 Aug 2006, 05:32
If xy is NOT=0, what is the value of x^4 y^2 -(xy)^2/x^3 andrecrompton 7 06 Jun 2006, 05:11
6 Experts publish their posts in the topic If xy not equal 0 and x^2*y^2 -xy = 6, which of the followin sperumba 6 18 Jan 2006, 19:15
Display posts from previous: Sort by

If x<=y and y = (x^2 - y^2)(x-y), then what is the value of

  Question banks Downloads My Bookmarks Reviews Important topics  

Moderators: Bunuel, WoundedTiger



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®.