GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 16 Oct 2019, 20:03

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.

Close

Request Expert Reply

Confirm Cancel

If 2x^2 - y^2 = 2xy, then (x+y)^2 =

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

Hide Tags

Find Similar Topics 
Retired Moderator
avatar
Status: Darden Class of 2013
Joined: 28 Jul 2009
Posts: 1789
Schools: University of Virginia
If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

Show Tags

New post 10 May 2010, 17:45
1
13
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

73% (01:45) correct 27% (02:38) wrong based on 498 sessions

HideShow timer Statistics

If 2x^2 - y^2 = 2xy, then (x+y)^2 =

A. x^2
B. 3x^2
C. 4xy
D. 2y^2
E. -y^2

_________________
Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58381
If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

Show Tags

New post 12 Nov 2010, 00:21
6
1
General Discussion
Manager
Manager
avatar
Joined: 12 Jan 2010
Posts: 223
Schools: DukeTuck,Kelogg,Darden
Reviews Badge
Re: please help solve this for me  [#permalink]

Show Tags

New post 10 May 2010, 17:50
2
Its B

2x^2 -y^2 = 2xy
2x^2 = 2xy + y^2

Add x^2 on both sides we get

2x^2 +x^2 = x^2 +y^2 +2xy
3x^2 = (x+y)^2
_________________
Run towards the things that make you uncomfortable daily. The greatest risk is not taking risks
http://gmatclub.com/forum/from-690-to-730-q50-v38-97356.html
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58381
If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

Show Tags

New post 10 May 2010, 17:53
2
5
bakfed wrote:
If 2x^2 - y^2 = 2xy, then (x+y)^2 =

A. x^2
B. 3x^2
C. 4xy
D. 2y^2
E. -y^2

OA


7. Algebra



Check below for more:
ALL YOU NEED FOR QUANT ! ! !
Ultimate GMAT Quantitative Megathread
_________________
Manager
Manager
avatar
Joined: 16 Feb 2010
Posts: 117
Re: please help solve this for me  [#permalink]

Show Tags

New post 18 May 2010, 09:17
1
bakfed wrote:
If 2x^2 - y^2 = 2xy, then (x+y)^2 =

A. x^2
B. 3x^2
C. 4xy
D. 2y^2
E. -y^2

OA

here we have to find the value of x^2 +y^2 +2xy in which 2xy
=2x^2 -y^2 (given ) hence ans is 3x^2.
Manager
Manager
User avatar
Joined: 01 Nov 2010
Posts: 111
Location: Zürich, Switzerland
Re: If 2x^2 –y^2 = 2xy  [#permalink]

Show Tags

New post 12 Nov 2010, 14:46
2x^2 –y^2 = 2xy
2x^2 = 2xy+y^2

3x^2 = x^2 + 2xy+y^2 (adding x^2 on both sides)

3x^2 = (x+y)^2


Answer:- B
Manager
Manager
User avatar
Joined: 25 Jan 2010
Posts: 99
Location: Calicut, India
Re: If 2x^2 –y^2 = 2xy  [#permalink]

Show Tags

New post 12 Nov 2010, 17:30
2x\(^2\)-y\(^2\)=2xy

(x+y)\(^2\)= x\(^2\)+2xy+y\(^2\)

replace 2xy by 2x\(^2\)-y\(^2\) and solve

Answer B.
_________________
If u think this post is useful plz feed me with a kudo
Manager
Manager
avatar
Joined: 23 Oct 2009
Posts: 62
Re: If 2x^2 –y^2 = 2xy  [#permalink]

Show Tags

New post 29 Dec 2010, 13:08
Sarang wrote:
2x^2 –y^2 = 2xy
2x^2 = 2xy+y^2

3x^2 = x^2 + 2xy+y^2 (adding x^2 on both sides)

3x^2 = (x+y)^2


Answer:- B


i didn't understand this pls explain
_________________
Consider giving Kudos if you liked my post. Thanks!
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58381
Re: If 2x^2 –y^2 = 2xy  [#permalink]

Show Tags

New post 29 Dec 2010, 13:33
SVP
SVP
User avatar
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1749
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
If 2x^2 –y^2 = 2xy, then (x+y)^2=  [#permalink]

Show Tags

New post 17 Jul 2014, 02:42
\(2x^2 – y^2 = 2xy\)

so, \(y^2 = 2x^2 - 2xy\) ............ (1)

\((x+y)^2 = x^2 + 2xy + y^2\)

Placing value of \(y^2\) from (1)

\(= x^2 + 2xy + 2x^2 - 2xy\)

\(= 3x^2\)

Answer = B
_________________
Kindly press "+1 Kudos" to appreciate :)
Intern
Intern
avatar
Joined: 20 Mar 2017
Posts: 1
Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

Show Tags

New post 24 Mar 2017, 05:30
Quite straight forward question

step 1:
(x+Y)^2 = X^2 +2xy + y^2

step 2:
now substitute 2xy from the equation.

(x+Y)^2 = X^2 +2x^2-y^2+y^2.

-y^2 and Y^2 cancels out

we are left with x^2+2X^2= 3X^2 Hence B.
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8085
Location: United States (CA)
Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

Show Tags

New post 27 Mar 2017, 17:22
1
bakfed wrote:
If 2x^2 - y^2 = 2xy, then (x+y)^2 =

A. x^2
B. 3x^2
C. 4xy
D. 2y^2
E. -y^2


We see that we are looking for the value of (x + y)^2 = x^2 + y^2 + 2xy.

We also see that 2x^2 - y^2 = 2xy; thus we can substitute for 2xy and we have:

x^2 + y^2 + 2x^2 - y^2 = 3x^2

Answer: B
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Intern
Intern
avatar
Joined: 24 Oct 2018
Posts: 10
Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

Show Tags

New post 24 Oct 2018, 07:36
Given: 2xy=2x2−y22xy=2x2−y2.

(x+y)2=x2+2xy+y2(x+y)2=x2+2xy+y2
substitute 2xy2xy
(x+y)2=x2+(2x2−y2)+y2=3x2(x+y)2=x2+(2x2−y2)+y2=3x2.

B.
GMAT Club Bot
Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 =   [#permalink] 24 Oct 2018, 07:36
Display posts from previous: Sort by

If 2x^2 - y^2 = 2xy, then (x+y)^2 =

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





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