Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 25 May 2017, 10:49

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# If x not eq to 0 and x=sqrt(4xy-4y^2) , then, in terms of y,

 post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
Director
Joined: 10 Oct 2005
Posts: 718
Followers: 4

Kudos [?]: 25 [0], given: 0

If x not eq to 0 and x=sqrt(4xy-4y^2) , then, in terms of y, [#permalink]

### Show Tags

17 Jan 2006, 05:15
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If x not eq to 0 and x=sqrt(4xy-4y^2) , then, in terms of y, x=
(A) 2y
(B) y
(C) y/2
(D) (-4y^2)/(1-2y)
(E) -2y
_________________

IE IMBA 2010

Last edited by Yurik79 on 17 Jan 2006, 08:17, edited 1 time in total.
Director
Joined: 17 Dec 2005
Posts: 547
Location: Germany
Followers: 1

Kudos [?]: 40 [0], given: 0

### Show Tags

17 Jan 2006, 07:05
Yurik,

are you sure that the stem and the answers are correct?

Plugged in the answers, but none of them is true.
SVP
Joined: 24 Sep 2005
Posts: 1885
Followers: 22

Kudos [?]: 323 [0], given: 0

Re: One more Algebra [#permalink]

### Show Tags

17 Jan 2006, 07:31
Yurik79 wrote:
If x not eq to 0 and x=sqrt(4xy-y^2) , then, in terms of y, x=
(A) 2y
(B) y
(C) y/2
(D) (-4y^2)/(1-2y)
(E) -2y

I guess there's some typo , it should be sqrt(2xy-y^2)
Anyway, we can solve to get the answer, even though the result doesn't appear among answer choices.
x^2 = [sqrt(4xy-y^2)] ^2 = 4xy- y^2
---> x^2-4xy+ y^2 = 0
We can consider this a quaratic equation of variable x and constant y so we can find x in term of y
Discriminant of this quadratic equation = 16y^2 - 4y^2 = 12 y^2
----> x= [4y + or - sqrt(12y^2)] / 2
= 2y + or - y*sqrt3= y ( 2-sqrt3) or y ( 2+sqrt3)
Director
Joined: 10 Oct 2005
Posts: 718
Followers: 4

Kudos [?]: 25 [0], given: 0

### Show Tags

17 Jan 2006, 08:17
Yurik,

are you sure that the stem and the answers are correct?

Plugged in the answers, but none of them is true.

Sorry my fault fixed the typo
_________________

IE IMBA 2010

SVP
Joined: 24 Sep 2005
Posts: 1885
Followers: 22

Kudos [?]: 323 [0], given: 0

Re: One more Algebra [#permalink]

### Show Tags

17 Jan 2006, 08:22
Yurik79 wrote:
If x not eq to 0 and x=sqrt(4xy-4y^2) , then, in terms of y, x=
(A) 2y
(B) y
(C) y/2
(D) (-4y^2)/(1-2y)
(E) -2y

x=sqrt(4xy-4y^2) ---> x^2= 4xy-4y^2 ---> x^2 - 4xy+4y^2 = (x-2y)^2 =0 ----> x = 2y
Director
Joined: 10 Oct 2005
Posts: 718
Followers: 4

Kudos [?]: 25 [0], given: 0

Re: One more Algebra [#permalink]

### Show Tags

17 Jan 2006, 08:27
laxieqv wrote:
Yurik79 wrote:
If x not eq to 0 and x=sqrt(4xy-4y^2) , then, in terms of y, x=
(A) 2y
(B) y
(C) y/2
(D) (-4y^2)/(1-2y)
(E) -2y

x=sqrt(4xy-4y^2) ---> x^2= 4xy-4y^2 ---> x^2 - 4xy+4y^2 = (x-2y)^2 =0 ----> x = 2y

Laxie, can you see the red hat on my avatar?I am taking it off !!!Good explanation!
The OA is A
_________________

IE IMBA 2010

Senior Manager
Joined: 13 Jun 2005
Posts: 252
Location: Haverhill, MA
Followers: 1

Kudos [?]: 17 [0], given: 0

### Show Tags

17 Jan 2006, 08:35
x = 2y

is my answere too.
CEO
Joined: 20 Nov 2005
Posts: 2898
Schools: Completed at SAID BUSINESS SCHOOL, OXFORD - Class of 2008
Followers: 25

Kudos [?]: 289 [0], given: 0

### Show Tags

17 Jan 2006, 15:41
A

Square both sides and we get

x^2 = 4xy-4y^2
i.e x^2 - 4xy + 4y^2 = 0
i.e (x -2y)^2 = 0

so x = 2y
_________________

SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

VP
Joined: 20 Sep 2005
Posts: 1018
Followers: 3

Kudos [?]: 36 [0], given: 0

### Show Tags

17 Jan 2006, 17:02
Squaring,

x^2 = 4yx - 4y^2 => x^2 - 4xy - y^2 = (x-2y)^2 = 0.
=> x = 2y.
17 Jan 2006, 17:02
Display posts from previous: Sort by

# If x not eq to 0 and x=sqrt(4xy-4y^2) , then, in terms of y,

 post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group and phpBB SEO 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®.