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

It is currently 19 Oct 2019, 08:37

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 x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =

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

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58445
If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =  [#permalink]

Show Tags

New post 07 Feb 2016, 10:07
1
3
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

90% (00:59) correct 10% (02:24) wrong based on 122 sessions

HideShow timer Statistics

Intern
Intern
avatar
Joined: 14 Jul 2015
Posts: 21
GMAT 1: 680 Q44 V40
GMAT 2: 710 Q49 V37
If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =  [#permalink]

Show Tags

New post Updated on: 10 Feb 2016, 17:15
The first thing we want to do is to write our desired solution in an alternative form. Doing so gives us \(x^2 - 2xy + y^2\). We see that we already have a piece of information which is similar to our desired solution: \(x^2 + y^2 = 14\). We then also see that we are provided with xy = 3. We plug in xy to get our desired form: \(x^2 - 2xy + y^2 = 14 - 2(3)\), which becomes \((x-y)^2 = 8\).

My answer is A, 8.

Edit: Fixed my answer according to the updated question

Originally posted by Beixi88 on 07 Feb 2016, 15:19.
Last edited by Beixi88 on 10 Feb 2016, 17:15, edited 1 time in total.
Math Expert
avatar
V
Joined: 02 Aug 2009
Posts: 7984
Re: If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =  [#permalink]

Show Tags

New post 07 Feb 2016, 18:43
1
Bunuel wrote:
If x^2 + y^2 = 14 and xy + 3, then (x − y)^2 =

A. 8
B. 11
C. 14
D. 17
E. 20


Hi Bunuel,
xy + 3 should be xy=3...
_________________
Math Expert
avatar
V
Joined: 02 Aug 2009
Posts: 7984
Re: If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =  [#permalink]

Show Tags

New post 07 Feb 2016, 18:45
Beixi88 wrote:
The first thing we want to do is to write our desired solution in an alternative form. Doing so gives us \(x^2 - 2xy + y^2\). We see that we already have a piece of information which is similar to our desired solution: \(x^2 + y^2 = 14\). We then also see that we are provided xy + 3, which becomes xy = -3. We plug in xy to get our desired form: \(x^2 - 2xy + y^2 = 14 - 2(-3)\), which becomes \((x-y)^2 = 20\).

My answer is E, 20.


Hi
there is a typo error ..
but you cannot take xy+ 3 to mean xy=-3..
only if xy+3=0, it will mean xy=-3..
rest your solution is perfect and you will get your correct answer as 14-2*3=8..
_________________
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58445
Re: If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =  [#permalink]

Show Tags

New post 10 Feb 2016, 11:07
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8109
Location: United States (CA)
Re: If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =  [#permalink]

Show Tags

New post 28 Feb 2018, 11:10
Bunuel wrote:
If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =

A. 8
B. 11
C. 14
D. 17
E. 20


(x - y)^2 = x^2 - 2xy + y^2 = 14 - 6 = 8.

Answer: A
_________________

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.

SVP
SVP
User avatar
V
Status: It's near - I can see.
Joined: 13 Apr 2013
Posts: 1686
Location: India
Concentration: International Business, Operations
Schools: INSEAD Jan '19
GPA: 3.01
WE: Engineering (Real Estate)
Reviews Badge CAT Tests
Re: If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =  [#permalink]

Show Tags

New post 17 Mar 2018, 00:23
Bunuel wrote:
If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =

A. 8
B. 11
C. 14
D. 17
E. 20


Expand (x − y)^2 = x^2 + y^2 - 2xy

Substitute the values, x^2 + y^2 = 14 & xy = 3

we get 14 -2(3)

8 (A)
_________________
"Do not watch clock; Do what it does. KEEP GOING."
Senior Manager
Senior Manager
User avatar
P
Joined: 07 Jul 2012
Posts: 367
Location: India
Concentration: Finance, Accounting
GPA: 3.5
Re: If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =  [#permalink]

Show Tags

New post 17 Mar 2018, 03:37
\(x^2\) + \(y^2\)= 14

xy= 3

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

= 14-2*3
= 14-6= 8

Answer: A.
_________________
Kindly hit kudos if my post helps!
GMAT Club Bot
Re: If x^2 + y^2 = 14 and xy = 3, then (x − y)^2 =   [#permalink] 17 Mar 2018, 03:37
Display posts from previous: Sort by

If x^2 + y^2 = 14 and xy = 3, 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