GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

It is currently 28 Mar 2020, 22:49

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 = y + 4 and x = 20 - y, then x^2 - y^2 =

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

Hide Tags

Find Similar Topics 
Manager
Manager
avatar
Joined: 03 Jan 2015
Posts: 72
GMAT ToolKit User
If x = y + 4 and x = 20 - y, then x^2 - y^2 =  [#permalink]

Show Tags

New post 23 May 2016, 00:49
1
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

91% (01:00) correct 9% (01:55) wrong based on 93 sessions

HideShow timer Statistics

If \(x = y + 4\) and \(x = 20 - y\), then \(x^2 - y^2\) =

(A) 16
(B) 80
(C) 144
(D) 256
(E) 384
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 62287
Re: If x = y + 4 and x = 20 - y, then x^2 - y^2 =  [#permalink]

Show Tags

New post 23 May 2016, 01:03
2
1
Math Expert
avatar
V
Joined: 02 Aug 2009
Posts: 8297
Re: If x = y + 4 and x = 20 - y, then x^2 - y^2 =  [#permalink]

Show Tags

New post 23 May 2016, 05:14
saiesta wrote:
If \(x = y + 4\) and \(x = 20 - y\), then \(x^2 - y^2\) =

(A) 16
(B) 80
(C) 144
(D) 256
(E) 384


Hi
another method would be to equate terms...
\(x = y + 4\) and \(x = 20 - y\), so \(y+4 = 20-y....................2y=16 .....................y=8\)
so \(x=y+4=12\)...
\(x^2 - y^2\) =\(12^2-8^2 = 144-64=80\)
B
_________________
Board of Directors
User avatar
D
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4880
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User
Re: If x = y + 4 and x = 20 - y, then x^2 - y^2 =  [#permalink]

Show Tags

New post 23 May 2016, 11:10
saiesta wrote:
If \(x = y + 4\) and \(x = 20 - y\), then \(x^2 - y^2\) =

(A) 16
(B) 80
(C) 144
(D) 256
(E) 384


\(x = y + 4\) => \(x - y = 4\)
\(x = 20 - y\) => \(x + y = 20\)

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

\(x^2 - y^2\) = ( \(4\) )( \(20\) )

\(x^2 - y^2\) = \(80\)

Hence answer will be option (B) 80
:-D
_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
GMAT Club Bot
Re: If x = y + 4 and x = 20 - y, then x^2 - y^2 =   [#permalink] 23 May 2016, 11:10
Display posts from previous: Sort by

If x = y + 4 and x = 20 - y, then x^2 - y^2 =

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





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