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

It is currently 19 Sep 2014, 00:24

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?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 22 Nov 2008
Posts: 22
Followers: 0

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

Is x^2 equal to xy? [#permalink] New post 15 Dec 2009, 22:28
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

71% (02:23) correct 29% (01:18) wrong based on 112 sessions
Is x^2 equal to xy?

(1) x^2 – y^2 = (x + 5)(y - 5)
(2) x = y
[Reveal] Spoiler: OA
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23471
Followers: 3500

Kudos [?]: 26400 [0], given: 2710

Re: ALGEBRA [#permalink] New post 16 Dec 2009, 05:39
Expert's post
dobinnoli wrote:
Is x^2 equal to xy?
(1) x^2 – y^2 = (x + 5)(y - 5)
(2) x = y
ANSWER IS D?


Question: is x^2=xy? --> x(x-y)=0 --> Equation holds true if x=0 or/and x=y.

So, basically question asks: Is x=0 or/and x=y true?

Obviously statement (2) is sufficient, as it gives directly that x=y.

(1) x^2-y^2 = (x + 5)(y - 5) --> (x+y)(x-y)=(x + 5)(y-5)

If y=5 --> (x+5)(x-5)=(x+5)(5-5) --> (x+5)(x-5)=0 --> Either x=5=y and in this case answer to the question is YES OR x=-5, hence x is not equal to y (nor to zero) and in this case answer to the question is NO. So two different answers.

Not sufficient.

Answer: B.
_________________

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

Intern
Intern
User avatar
Joined: 03 Mar 2010
Posts: 40
Followers: 1

Kudos [?]: 10 [0], given: 1

Re: Algebra DS [#permalink] New post 02 Aug 2010, 07:08
Statement 1:
(x,y)=(5,5) --> x²=xy
(x,y)=(-5,5) --> x²<>xy
not sufficient

Statement 2:
x=y --> xx=xy or x²=xy
sufficient

B
_________________

Hardworkingly, you like my post, so kudos me.

Intern
Intern
avatar
Joined: 10 Apr 2008
Posts: 25
Followers: 0

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

Re: Algebra DS [#permalink] New post 02 Aug 2010, 19:23
I agree with bogos.

Stmt1:
x^2 - y^2 = (x+5)(x-5)
x^2 - y^2 = x^2 - 25
0 = y^2 - 25
y = +5, -5

plugin a possible value of y into the equation x^2 - y^2 = x^2 - 25
you can see when that y can be -5 and x can 5. But plugging in the same value into x^2 = xy would yield 25 = -25.
Intern
Intern
avatar
Joined: 11 Oct 2009
Posts: 14
Concentration: Operations, Finance
GPA: 3.09
Followers: 0

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

Re: ALGEBRA [#permalink] New post 03 Oct 2010, 23:21
X=5 =>> y=+/-5
But if you substitute back in eqn only y=5 is valid

Please post OA
Director
Director
avatar
Joined: 29 Nov 2012
Posts: 930
Followers: 11

Kudos [?]: 273 [0], given: 543

Is X^2 equal to xy? [#permalink] New post 26 Sep 2013, 07:00
Is X^2 equal to xy?

1) X^2 - Y^2 = ( x+5) ( y-5)
2) x=y


[Reveal] Spoiler:
Fairly easy question but I was wondering how do manipulate statement 1 am I missing something cos it seems insufficient on surface without any calculations?

_________________

Click +1 Kudos if my post helped...

Amazing Free video explanation for all Quant questions from OG 13 and much more http://www.gmatquantum.com/og13th/

GMAT Prep software What if scenarios gmat-prep-software-analysis-and-what-if-scenarios-146146.html

Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23471
Followers: 3500

Kudos [?]: 26400 [0], given: 2710

Re: Is X^2 equal to xy? [#permalink] New post 26 Sep 2013, 07:37
Expert's post
fozzzy wrote:
Is X^2 equal to xy?

1) X^2 - Y^2 = ( x+5) ( y-5)
2) x=y


[Reveal] Spoiler:
Fairly easy question but I was wondering how do manipulate statement 1 am I missing something cos it seems insufficient on surface without any calculations?


Merging similar topics.
_________________

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

SVP
SVP
User avatar
Joined: 06 Sep 2013
Posts: 1666
Location: United States
Concentration: Finance
GMAT 1: 710 Q48 V39
WE: Corporate Finance (Investment Banking)
Followers: 12

Kudos [?]: 164 [0], given: 274

GMAT ToolKit User
Re: Is x^2 equal to xy? [#permalink] New post 02 Feb 2014, 16:06
dobinnoli wrote:
Is x^2 equal to xy?

(1) x^2 – y^2 = (x + 5)(y - 5)
(2) x = y


Is x(x-y)=0

So is x=0 or x=y?

Statement 1

Obviously x is not equal to y otherwise LHS and RHS should be zero

Is x = 0

Is -y^2 = -25, could be but we don't know

Statement 2

x=y, yes. This is correct and sufficient

B
Re: Is x^2 equal to xy?   [#permalink] 02 Feb 2014, 16:06
    Similar topics Author Replies Last post
Similar
Topics:
Is X^2 equal to xy? fozzzy 0 26 Sep 2013, 07:00
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
Is x^2 equal to xy? (1) x^2-y^2 = (x + 5)(y - 5) (2) x = y Yurik79 9 09 Feb 2006, 06:09
Display posts from previous: Sort by

Is x^2 equal to xy?

  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®.