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

It is currently 22 Oct 2014, 22:13

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^2 + y^2? 1) x^2 + y^2 = 2xy + 1 2)

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 03 Feb 2010
Posts: 29
Schools: HBS
Followers: 0

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

What is the value of x^2 + y^2? 1) x^2 + y^2 = 2xy + 1 2) [#permalink] New post 24 Jul 2010, 07:50
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

67% (01:37) correct 33% (00:44) wrong based on 6 sessions
What is the value of x^2 + y^2?
1) x^2 + y^2 = 2xy + 1
2) x^2 + y^2 = 4 - 2xy

My question is why can't the answer be C?
Adding 1 and 2,
2 (x^2 + y^2 ) = 5
Therefore x^2 + y^2 = 5/2

Am I am missing something obvious here?
[Reveal] Spoiler: OA
Intern
Intern
avatar
Joined: 10 Apr 2008
Posts: 25
Followers: 0

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

Re: DS from Sackmann's Challenge Algrebra Set [#permalink] New post 24 Jul 2010, 09:40
I also got C using the same method as youven.

S1 can be simplified to say (x-y)^2 = 1. That means (x-y) can be -1 or +1.
Similarly, S2 can be simplified to say (x-y)^2 = 4. That means (x+y) can be -2 or +2.

Solving for x and y, I get x=3/2 or x=-3/2 and y=1/2 or y=-1/2. For all the possible values of x and y, x^2 + y^2 will only be one value.

Can you someone help identify what I am doing wrong?

Thanks
CEO
CEO
User avatar
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2794
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Followers: 182

Kudos [?]: 987 [0], given: 235

Reviews Badge
Re: DS from Sackmann's Challenge Algrebra Set [#permalink] New post 24 Jul 2010, 10:32
seems to be C only.

Please check the question again,and if possible post OE
_________________

Fight for your dreams :For all those who fear from Verbal- lets give it a fight

Money Saved is the Money Earned :)

Jo Bole So Nihaal , Sat Shri Akaal

:thanks Support GMAT Club by putting a GMAT Club badge on your blog/Facebook :thanks

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Gmat test review :
670-to-710-a-long-journey-without-destination-still-happy-141642.html

Intern
Intern
avatar
Joined: 03 Feb 2010
Posts: 29
Schools: HBS
Followers: 0

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

Re: DS from Sackmann's Challenge Algrebra Set [#permalink] New post 24 Jul 2010, 11:00
Answer is E. Emailed Sackamnn asking for an explanation, waiting for a reply...
Manager
Manager
avatar
Joined: 03 Jun 2010
Posts: 184
Location: United States (MI)
Concentration: Marketing, General Management
WE: Business Development (Consumer Products)
Followers: 4

Kudos [?]: 22 [0], given: 40

GMAT ToolKit User
Re: DS from Sackmann's Challenge Algrebra Set [#permalink] New post 26 Jul 2010, 03:39
(E)
Can't uderstand how you got (C)-)
Intern
Intern
avatar
Joined: 03 Feb 2010
Posts: 29
Schools: HBS
Followers: 0

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

Re: DS from Sackmann's Challenge Algrebra Set [#permalink] New post 26 Jul 2010, 06:38
ulm wrote:
(E)
Can't uderstand how you got (C)-)

well just read my first post and you will see how i came up with C
Manager
Manager
avatar
Joined: 17 Oct 2008
Posts: 199
Followers: 1

Kudos [?]: 13 [0], given: 11

Re: DS from Sackmann's Challenge Algrebra Set [#permalink] New post 26 Jul 2010, 09:07
I am getting C again..

will be good to hear from Sackmann! :)
Re: DS from Sackmann's Challenge Algrebra Set   [#permalink] 26 Jul 2010, 09:07
    Similar topics Author Replies Last post
Similar
Topics:
What is the value of x^2 + y^2 ? (1) x^2+ y^2 = 2xy + 1 (2) dreambeliever 4 05 Jun 2011, 08:16
What is the value of x^2 + y^2? (1) x^2 + y^2 = 2xy +1 (2) lumone 1 28 Jan 2009, 10:57
Experts publish their posts in the topic If R=1+2xy+(x^2)(y^2), what is the value of xy? (1) R=0 (2) mbsnyc 3 19 Dec 2007, 11:56
R = 1 + 2xy + x^2y^2; what is value of xy? 1.) R = 0 2.) uphillclimb 2 14 Oct 2006, 11:53
What is the value of x^2 + 2xy + y^2? 1) x + y = 7 2) x = 2 john2005 6 18 Apr 2006, 18:13
Display posts from previous: Sort by

What is the value of x^2 + y^2? 1) x^2 + y^2 = 2xy + 1 2)

  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®.