Find all School-related info fast with the new School-Specific MBA Forum

It is currently 30 Jul 2014, 01:12

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If x^2/9 – 4/y^2 = 12, what is the value of x?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 11 Aug 2009
Posts: 129
Followers: 1

Kudos [?]: 17 [0], given: 3

GMAT Tests User
If x^2/9 – 4/y^2 = 12, what is the value of x? [#permalink] New post 18 Nov 2009, 20:33
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

42% (01:48) correct 58% (00:45) wrong based on 25 sessions
If x^2/9 – 4/y^2 = 12, what is the value of x?

(1) x/3 + 2/y = 6

(2) x/3 – 2/y = 2
[Reveal] Spoiler: OA

Last edited by Bunuel on 27 Jul 2014, 22:59, edited 1 time in total.
Edited the question and added the OA.
Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2009
Posts: 291
Location: India
Concentration: General Management
Followers: 2

Kudos [?]: 87 [0], given: 5

GMAT Tests User
Re: If x^2/9 – 4/y^2 = 12, what is the value of x? [#permalink] New post 18 Nov 2009, 20:47
kairoshan wrote:
If x2/9 – 4/y2 = 12, what is the value of x?

(1) x/3 + 2/y = 6

(2) x/3 – 2/y = 2



E

the original equation is (x/3 + 2/y) (x/3 – 2/y) = 12 and option 1 and 2 provide values of individual expressions. both are insuff alone and together
4 KUDOS received
GMAT Instructor
avatar
Joined: 24 Jun 2008
Posts: 967
Location: Toronto
Followers: 247

Kudos [?]: 633 [4] , given: 3

GMAT Tests User
Re: If x^2/9 – 4/y^2 = 12, what is the value of x? [#permalink] New post 18 Nov 2009, 21:19
4
This post received
KUDOS
kairoshan wrote:
If x2/9 – 4/y2 = 12, what is the value of x?

(1) x/3 + 2/y = 6

(2) x/3 – 2/y = 2


The factorization kp1811 gives above is the key to the problem, but the answer is not E. First, as kp1811 points out above, the expression in the stem can be factored; it's a difference of squares:

\frac{x^2}{9} - \frac{4}{y^2} = \left( \frac{x}{3} + \frac{2}{y} \right) \left( \frac{x}{3} - \frac{2}{y} \right)

We know this is equal to 12. Now, using statement 1 alone, we can substitute:

\begin{align*}
\left( \frac{x}{3} + \frac{2}{y} \right) \left( \frac{x}{3} - \frac{2}{y} \right) &= 12 \\
(6)\left( \frac{x}{3} - \frac{2}{y} \right) &= 12 \\
\frac{x}{3} - \frac{2}{y} &= 2
\end{align*}


That is, using Statement 1 alone, we can derive the equation in Statement 2. Now if we know both of these equations are true:

\begin{align*}
\frac{x}{3} + \frac{2}{y} &= 6 \\
\frac{x}{3} - \frac{2}{y} &= 2
\end{align*}

we can just add these equations to find that \frac{2x}{3} = 8, so x = 12. So Statement 1 alone is sufficient.

Statement 2 alone is also sufficient; the analysis is identical to the above. So the answer is D.
_________________

Nov 2011: After years of development, I am now making my advanced Quant books and high-level problem sets available for sale. Contact me at ianstewartgmat at gmail.com for details.

Private GMAT Tutor based in Toronto

1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2009
Posts: 291
Location: India
Concentration: General Management
Followers: 2

Kudos [?]: 87 [1] , given: 5

GMAT Tests User
Re: If x^2/9 – 4/y^2 = 12, what is the value of x? [#permalink] New post 19 Nov 2009, 03:09
1
This post received
KUDOS
IanStewart wrote:
kairoshan wrote:
If x2/9 – 4/y2 = 12, what is the value of x?

(1) x/3 + 2/y = 6

(2) x/3 – 2/y = 2


The factorization kp1811 gives above is the key to the problem, but the answer is not E. First, as kp1811 points out above, the expression in the stem can be factored; it's a difference of squares:

\frac{x^2}{9} - \frac{4}{y^2} = \left( \frac{x}{3} + \frac{2}{y} \right) \left( \frac{x}{3} - \frac{2}{y} \right)

We know this is equal to 12. Now, using statement 1 alone, we can substitute:

\begin{align*}
\left( \frac{x}{3} + \frac{2}{y} \right) \left( \frac{x}{3} - \frac{2}{y} \right) &= 12 \\
(6)\left( \frac{x}{3} - \frac{2}{y} \right) &= 12 \\
\frac{x}{3} - \frac{2}{y} &= 2
\end{align*}


That is, using Statement 1 alone, we can derive the equation in Statement 2. Now if we know both of these equations are true:

\begin{align*}
\frac{x}{3} + \frac{2}{y} &= 6 \\
\frac{x}{3} - \frac{2}{y} &= 2
\end{align*}

we can just add these equations to find that \frac{2x}{3} = 8, so x = 12. So Statement 1 alone is sufficient.

Statement 2 alone is also sufficient; the analysis is identical to the above. So the answer is D.


darn me :x ...it should be D just adding option 1 and 2 gives value of x :oops: :( :cry:
SVP
SVP
User avatar
Joined: 09 Sep 2013
Posts: 1807
Followers: 167

Kudos [?]: 33 [0], given: 0

Premium Member
Re: If x^2/9 – 4/y^2 = 12, what is the value of x? [#permalink] New post 27 Jul 2014, 17:29
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

Re: If x^2/9 – 4/y^2 = 12, what is the value of x?   [#permalink] 27 Jul 2014, 17:29
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic What is the value of x^2 - 4y^2? derekgmat 3 08 Nov 2012, 02:10
1 If (x^2)/9 - 4/(y^2) = 12, what is the value of x? (1) x/3 + brokerbevo 12 05 Aug 2008, 13:02
1 If x2/9 4/y2 = 12, what is the value of x? (1) x/3 + 2/y = 6 judokan 11 25 Jul 2008, 23:46
1 If x^2/9 4/y^2 = 12, what is the value of x? (1) x/3 + 2/y = jimmyjamesdonkey 4 30 Jun 2008, 12:46
If x2/9 4/y2 = 12, what is the value of x? (1) x/3 + 2/y = 6 ArvGMAT 1 24 Jun 2007, 16:57
Display posts from previous: Sort by

If x^2/9 – 4/y^2 = 12, what is the value of x?

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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®.