It is currently 21 Apr 2019, 06:05
My Tests

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.

Both x and y are positive integers.

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Founder
Founder
User avatar
Joined: 18 Apr 2015
Posts: 6200
Followers: 99

Kudos [?]: 1199 [0], given: 5712

CAT Tests
Both x and y are positive integers. [#permalink] New post 09 Apr 2019, 02:16
Expert's post
00:00

Question Stats:

100% (01:41) correct 0% (00:00) wrong based on 1 sessions
Both x and y are positive integers. If \(x^2 + 2xy + y^2 = 49\) and x\(^2 −   y^2 = − 7\), then \(y =  \)

A. 2

B. 3

C. 4

D. 5

E. 7
[Reveal] Spoiler: OA

_________________

Get the 2 FREE GREPrepclub Tests

1 KUDOS received
GRE Instructor
User avatar
Joined: 10 Apr 2015
Posts: 1647
Followers: 57

Kudos [?]: 1575 [1] , given: 8

CAT Tests
Re: Both x and y are positive integers. [#permalink] New post 09 Apr 2019, 06:26
1
This post received
KUDOS
Expert's post
Carcass wrote:
Both x and y are positive integers. If \(x^2 + 2xy + y^2 = 49\) and x\(^2 −   y^2 = − 7\), then \(y =  \)

A. 2

B. 3

C. 4

D. 5

E. 7


GIVEN: x² + 2xy + y² = 49
Factor to get: (x + y)² = 49

So, EITHER x + y = 7 OR x + y = -7
Since we're told that x and y are POSITIVE, we can be certain that x + y = 7


GIVEN: x² - y² = −7
Factor to get: (x + y)(x - y) = -7
Replace x + y with 7 to get: (7)(x - y) = -7
So, we know that x - y = -1

We now have two linear equations:
x + y = 7
x - y = -1

Subtract the BOTTOM equation from the TOP equation to get: 2y = 8
Solve: y = 8/2 = 4

Answer: C

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com
Image
Sign up for our free GRE Question of the Day emails

Re: Both x and y are positive integers.   [#permalink] 09 Apr 2019, 06:26
Display posts from previous: Sort by

Both x and y are positive integers.

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

GRE Prep Club Forum Home| About| Terms and Conditions and Privacy Policy| GRE Prep Club Rules| Contact

Powered by phpBB © phpBB Group

Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.