It is currently 23 Sep 2017, 05:54

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

x/y condition

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
VP
VP
User avatar
Joined: 18 May 2008
Posts: 1262

Kudos [?]: 511 [0], given: 0

x/y condition [#permalink]

Show Tags

New post 26 Feb 2009, 10:31
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

I have read in some question that \(x/y <=1\) MUST be true for all positive values if \(x\) is a prime factor of \(y^2\)
Is this a standard formula?

Kudos [?]: 511 [0], given: 0

SVP
SVP
User avatar
Joined: 07 Nov 2007
Posts: 1795

Kudos [?]: 1034 [0], given: 5

Location: New York
Re: x/y condition [#permalink]

Show Tags

New post 26 Feb 2009, 10:56
ritula wrote:
I have read in some question that \(x/y <=1\) MUST be true for all positive values if \(x\) is a prime factor of \(y^2\)
Is this a standard formula?


y^2 = k*x = l^2*x*x { here k= l^2*x to make RHS perfect square.}

y = (lx)

x/y =1/l (clearly L is >=1)

so
\(x/y <=1\)
must be true.
_________________

Your attitude determines your altitude
Smiling wins more friends than frowning

Kudos [?]: 1034 [0], given: 5

Manager
Manager
User avatar
Joined: 26 Dec 2008
Posts: 58

Kudos [?]: 14 [0], given: 0

Schools: Booth (Admit R1), Sloan (Ding R1), Tuck (R1)
Re: x/y condition [#permalink]

Show Tags

New post 26 Feb 2009, 16:03
x2suresh wrote:
ritula wrote:
I have read in some question that \(x/y <=1\) MUST be true for all positive values if \(x\) is a prime factor of \(y^2\)
Is this a standard formula?


y^2 = k*x = l^2*x*x { here k= l^2*x to make RHS perfect square.}

y = (lx)

x/y =1/l (clearly L is >=1)

so
\(x/y <=1\)
must be true.


Was thinking along the same lines, but how can we justify that y = whole number? What if y = sqrt(5), and x = 5? or y = sqrt(10) and x = 5?

Thx

Kudos [?]: 14 [0], given: 0

SVP
SVP
User avatar
Joined: 07 Nov 2007
Posts: 1795

Kudos [?]: 1034 [0], given: 5

Location: New York
Re: x/y condition [#permalink]

Show Tags

New post 26 Feb 2009, 18:58
xyz21 wrote:
x2suresh wrote:
ritula wrote:
I have read in some question that \(x/y <=1\) MUST be true for all positive values if \(x\) is a prime factor of \(y^2\)
Is this a standard formula?


y^2 = k*x = l^2*x*x { here k= l^2*x to make RHS perfect square.}

y = (lx)

x/y =1/l (clearly L is >=1)

so
\(x/y <=1\)
must be true.


Was thinking along the same lines, but how can we justify that y = whole number? What if y = sqrt(5), and x = 5? or y = sqrt(10) and x = 5?

Thx


above rule is valid only if Y is integer..
_________________

Your attitude determines your altitude
Smiling wins more friends than frowning

Kudos [?]: 1034 [0], given: 5

SVP
SVP
User avatar
Joined: 07 Nov 2007
Posts: 1795

Kudos [?]: 1034 [0], given: 5

Location: New York
Re: x/y condition [#permalink]

Show Tags

New post 26 Feb 2009, 18:58
xyz21 wrote:
x2suresh wrote:
ritula wrote:
I have read in some question that \(x/y <=1\) MUST be true for all positive values if \(x\) is a prime factor of \(y^2\)
Is this a standard formula?


y^2 = k*x = l^2*x*x { here k= l^2*x to make RHS perfect square.}

y = (lx)

x/y =1/l (clearly L is >=1)

so
\(x/y <=1\)
must be true.


Was thinking along the same lines, but how can we justify that y = whole number? What if y = sqrt(5), and x = 5? or y = sqrt(10) and x = 5?

Thx


above rule is valid only if Y is integer..
_________________

Your attitude determines your altitude
Smiling wins more friends than frowning

Kudos [?]: 1034 [0], given: 5

SVP
SVP
avatar
Joined: 17 Jun 2008
Posts: 1540

Kudos [?]: 278 [0], given: 0

Re: x/y condition [#permalink]

Show Tags

New post 28 Feb 2009, 17:01
I agree with xyz1. It is not mentioned whether y is an integer. Hence, the given inequality may or may not be true.

In geenral, if x is a prime factor of y, then x/y <= 1 will always be true as x <= y.

For example, x = 2, y = 2
or, x = 3, y = 6
and so on.

Kudos [?]: 278 [0], given: 0

SVP
SVP
User avatar
Joined: 29 Aug 2007
Posts: 2473

Kudos [?]: 834 [0], given: 19

Re: x/y condition [#permalink]

Show Tags

New post 01 Mar 2009, 07:15
ritula wrote:
I have read in some question that \(x/y <= 1\) MUST be true for all positive values if \(x\) is a prime factor of \(y^2\)
Is this a standard formula?


Agree that the relationship doesnot hold true.

Since x and y^2 are but y could be +ve or -ve number, (x/y) <= 1 or y.

Did you get the question correctly, ritula?

Either "\(x/y <= 1\) should be x/y^2 <= 1" or "y^2 is y".
_________________

Verbal: http://gmatclub.com/forum/new-to-the-verbal-forum-please-read-this-first-77546.html
Math: http://gmatclub.com/forum/new-to-the-math-forum-please-read-this-first-77764.html
Gmat: http://gmatclub.com/forum/everything-you-need-to-prepare-for-the-gmat-revised-77983.html


GT

Kudos [?]: 834 [0], given: 19

VP
VP
User avatar
Joined: 18 May 2008
Posts: 1262

Kudos [?]: 511 [0], given: 0

Re: x/y condition [#permalink]

Show Tags

New post 01 Mar 2009, 09:10
The statement is correct
GMAT TIGER wrote:
ritula wrote:
I have read in some question that \(x/y <= 1\) MUST be true for all positive values if \(x\) is a prime factor of \(y^2\)
Is this a standard formula?


Agree that the relationship doesnot hold true.

Since x and y^2 are but y could be +ve or -ve number, (x/y) <= 1 or y.

Did you get the question correctly, ritula?

Either "\(x/y <= 1\) should be x/y^2 <= 1" or "y^2 is y".

Kudos [?]: 511 [0], given: 0

Re: x/y condition   [#permalink] 01 Mar 2009, 09:10
Display posts from previous: Sort by

x/y condition

  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®.