It is currently 12 Dec 2017, 17:49

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If x² - y² = 55, and x - y = 11, then y =

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

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42571

Kudos [?]: 135394 [0], given: 12691

If x² - y² = 55, and x - y = 11, then y = [#permalink]

Show Tags

New post 12 May 2016, 00:58
Expert's post
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

78% (01:13) correct 22% (01:00) wrong based on 125 sessions

HideShow timer Statistics

Kudos [?]: 135394 [0], given: 12691

1 KUDOS received
Intern
Intern
avatar
Joined: 07 May 2016
Posts: 26

Kudos [?]: 5 [1], given: 1

If x² - y² = 55, and x - y = 11, then y = [#permalink]

Show Tags

New post 12 May 2016, 06:10
1
This post received
KUDOS
1
This post was
BOOKMARKED
Bunuel wrote:
If x^2 - y^2 = 55, and x - y = 11, then y =

A. 8
B. 5
C. 3
D. -8
E. -3



Hi
we have x - y = 11
=> x = 11+y
replace x into the first equation
=>\((11+y)^2 - y^2 = 55\)
EXPANDING:
=>\((11)^2 + 2*(11)*y + y^2 - y^2 = 55\)
=>\(121 + 22y = 55\)
=>\(22y = 55 - 121\)
=>\(22y = -66\)
=>\(y = -66/22 = -3\)
=> answer is E (-3)

Last edited by HungNguyen on 12 May 2016, 07:18, edited 1 time in total.

Kudos [?]: 5 [1], given: 1

Board of Directors
User avatar
G
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3106

Kudos [?]: 1144 [0], given: 327

Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: If x² - y² = 55, and x - y = 11, then y = [#permalink]

Show Tags

New post 12 May 2016, 06:56
Bunuel wrote:
If x^2 - y^2 = 55, and x - y = 11, then y =

A. 8
B. 5
C. 3
D. -8
E. -3


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

\(55\) = \(( 11 )( x + y )\)

\(5\) = \(x + y\)-------> (1)

\(11\) = \(x - y\)-------> (2)

\(2x\) = \(16\)

Or, \(x\) = \(8\)

SO,\(y\) = \(-3\)

Hence answer will be (E)

_________________

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 )

Kudos [?]: 1144 [0], given: 327

Current Student
User avatar
Joined: 18 Oct 2014
Posts: 903

Kudos [?]: 454 [0], given: 69

Location: United States
GMAT 1: 660 Q49 V31
GPA: 3.98
GMAT ToolKit User
Re: If x² - y² = 55, and x - y = 11, then y = [#permalink]

Show Tags

New post 12 May 2016, 10:29
(x+y)(x-y)= 55

x+y= 5 (its given that (x-y)= 11)

Solving two equations:-

x+y=5
x-y=11

y= -3
_________________

I welcome critical analysis of my post!! That will help me reach 700+

Kudos [?]: 454 [0], given: 69

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 14897

Kudos [?]: 287 [0], given: 0

Premium Member
Re: If x² - y² = 55, and x - y = 11, then y = [#permalink]

Show Tags

New post 15 Oct 2017, 08:49
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Kudos [?]: 287 [0], given: 0

Re: If x² - y² = 55, and x - y = 11, then y =   [#permalink] 15 Oct 2017, 08:49
Display posts from previous: Sort by

If x² - y² = 55, and x - y = 11, then y =

  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®.