It is currently 22 Feb 2018, 00:25

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

(x-y)2=?

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

Hide Tags

Expert Post
Math Revolution GMAT Instructor
User avatar
D
Joined: 16 Aug 2015
Posts: 4898
GPA: 3.82
(x-y)2=? [#permalink]

Show Tags

New post 09 Feb 2017, 04:26
Expert's post
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

62% (00:50) correct 38% (01:04) wrong based on 52 sessions

HideShow timer Statistics

\((x-y)^2=?\)

\(1) x^2+y^2=8\)
\(2) (x+y)^2=4xy\)
[Reveal] Spoiler: OA

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Senior Manager
Senior Manager
User avatar
G
Joined: 19 Apr 2016
Posts: 275
Location: India
GMAT 1: 570 Q48 V22
GMAT 2: 640 Q49 V28
GPA: 3.5
WE: Web Development (Computer Software)
(x-y)2=? [#permalink]

Show Tags

New post 09 Feb 2017, 04:34
MathRevolution wrote:
\((x-y)^2=?\)

\(1) x^2+y^2=8\)
\(2) (x+y)^2=4xy\)



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

St I
\(x^2+y^2=8\) =>\((x-y)^2= 8-2xy\) ----------Insufficient

St II
\((x+y)^2=4xy\) => \(x^2+y^2 + 2xy=4xy\) => \(x^2+y^2 =2xy\)
Therefore we have, \((x-y)^2= x^2+y^2-2xy\) =>\((x-y)^2= 2xy-2xy\) =0 ----------Sufficient

Hence Option B is correct.
Hit Kudos if you liked it 8-)
Expert Post
Math Revolution GMAT Instructor
User avatar
D
Joined: 16 Aug 2015
Posts: 4898
GPA: 3.82
Re: (x-y)2=? [#permalink]

Show Tags

New post 12 Feb 2017, 17:20
==> If you modify the original condition and the question, from \((x-y)^2=x^2+y^2-2xy=x^2+y^2+2xy-4xy= (x+y)^2-4xy\), con 2) is sufficient.

Therefore, the answer is B.
Answer: B
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Director
Director
avatar
P
Joined: 14 Nov 2014
Posts: 650
Re: (x-y)2=? [#permalink]

Show Tags

New post 13 Feb 2017, 00:22
MathRevolution wrote:
\((x-y)^2=?\)

\(1) x^2+y^2=8\)
\(2) (x+y)^2=4xy\)



A--Not suff
B-(x+y)^2 = 4xy
x^2 + y^2 +2xy =4xy
x^2 + y^2 - 2xy = 0
(x-y)^2 = 0
Suff.
hence B
Re: (x-y)2=?   [#permalink] 13 Feb 2017, 00:22
Display posts from previous: Sort by

(x-y)2=?

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


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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®.