It is currently 19 Nov 2017, 11:05

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# What is the value of x^2 + y^2 ?

 post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Manager
Joined: 24 Jun 2010
Posts: 140

Kudos [?]: 41 [0], given: 26

Concentration: Strategy, Technology
What is the value of x^2 + y^2 ? [#permalink]

### Show Tags

04 Oct 2010, 18:06
1
This post was
BOOKMARKED
00:00

Difficulty:

55% (hard)

Question Stats:

60% (01:16) correct 40% (01:22) wrong based on 133 sessions

### HideShow timer Statistics

What is the value of $$x^2 + y^2$$?

1. $$x^2 + y^2 = 2xy + 1$$
2. $$x^2 + y^2 = 4 - 2xy$$

OPEN DISCUSSION OF THIS QUESTION IS HERE: what-is-the-value-of-x-2-y-142923.html
[Reveal] Spoiler: OA

Last edited by Bunuel on 24 Nov 2014, 01:45, edited 1 time in total.
Edited the OA.

Kudos [?]: 41 [0], given: 26

Retired Moderator
Joined: 02 Sep 2010
Posts: 793

Kudos [?]: 1208 [0], given: 25

Location: London
Re: What is the value of x^2 + y^2 ? [#permalink]

### Show Tags

04 Oct 2010, 18:51
1) it's given in terms of xy, insufficient

2) again same problem, insufficient

1+2) add together the equations and divide by 2. X^2+y^2=2.5
sufficient

Posted from my mobile device
_________________

Kudos [?]: 1208 [0], given: 25

Manager
Joined: 24 Jun 2010
Posts: 140

Kudos [?]: 41 [0], given: 26

Concentration: Strategy, Technology
Re: What is the value of x^2 + y^2 ? [#permalink]

### Show Tags

04 Oct 2010, 19:34
shrouded1 wrote:
1) it's given in terms of xy, insufficient

2) again same problem, insufficient

1+2) add together the equations and divide by 2. X^2+y^2=2.5
sufficient

Posted from my mobile device

Yup I get the same thing.. OA must be wrong

Kudos [?]: 41 [0], given: 26

Intern
Joined: 27 Jul 2010
Posts: 20

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

Location: Bangalore
Re: What is the value of x^2 + y^2 ? [#permalink]

### Show Tags

04 Oct 2010, 20:37
Yes.. I get C too.. OA must be wrong..
_________________

Nothing is free.. You 've to earn it!!!

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

Manager
Joined: 19 Sep 2010
Posts: 172

Kudos [?]: 99 [0], given: 18

Re: What is the value of x^2 + y^2 ? [#permalink]

### Show Tags

16 Oct 2010, 07:14
shd be C according to me as well...

Kudos [?]: 99 [0], given: 18

Manager
Joined: 27 Aug 2014
Posts: 102

Kudos [?]: 119 [0], given: 19

Concentration: Finance, Strategy
GPA: 3.9
WE: Analyst (Energy and Utilities)
Re: What is the value of x^2 + y^2 ? [#permalink]

### Show Tags

23 Nov 2014, 08:50
I also end up with C.

Kudos [?]: 119 [0], given: 19

Math Expert
Joined: 02 Sep 2009
Posts: 42257

Kudos [?]: 132700 [0], given: 12335

Re: What is the value of x^2 + y^2 ? [#permalink]

### Show Tags

24 Nov 2014, 01:45
krazo wrote:
What is the value of $$x^2 + y^2$$?

1. $$x^2 + y^2 = 2xy + 1$$
2. $$x^2 + y^2 = 4 - 2xy$$

What is the value of x^2+y^2 ?

(1) x^2+y^2=2xy+1 --> $$x^2-2xy+y^2=1$$ --> $$(x-y)^2=1$$. If $$x=1$$ and $$y=0$$, then $$x^2+y^2=1$$ but if $$x=2$$ and $$y=1$$, then $$x^2+y^2=5$$. Not sufficient.

(2) x^2+y^2=4-2xy --> $$x^2+2xy+y^2=4$$ --> $$(x+y)^2=4$$. If $$x=2$$ and $$y=0$$, then $$x^2+y^2=4$$ but if $$x=1$$ and $$y=1$$, then $$x^2+y^2=2$$. Not sufficient.

(1)+(2) Sum the equations: $$2(x^2+y^2)=5$$ --> $$x^2+y^2=2.5$$. Sufficient.

OPEN DISCUSSION OF THIS QUESTION IS HERE: what-is-the-value-of-x-2-y-142923.html
_________________

Kudos [?]: 132700 [0], given: 12335

Re: What is the value of x^2 + y^2 ?   [#permalink] 24 Nov 2014, 01:45
Display posts from previous: Sort by

# What is the value of x^2 + y^2 ?

 post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne 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®.