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

It is currently 25 Oct 2014, 08:05

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

Is square root of x*y an integer? 1). Root x is not an

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
avatar
Joined: 17 Oct 2005
Posts: 940
Followers: 1

Kudos [?]: 35 [0], given: 0

Is square root of x*y an integer? 1). Root x is not an [#permalink] New post 07 Jan 2006, 16:58
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Is square root of x*y an integer?
1). Root x is not an integer
2). Root y is not an integer
Intern
Intern
avatar
Joined: 13 Nov 2005
Posts: 32
Followers: 0

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

 [#permalink] New post 07 Jan 2006, 17:32
For sqrt(xy) to be an integer:

xy must be an integer AND
either xy must be a perfect square or x and y must each be perfect squares.

(1) and (2) don't give all this information.

Hence answer = E

I'm not sure about my explanation though .. does anyone agree?

Thanks
_________________

Help me crack the GMAT .. !!

SVP
SVP
avatar
Joined: 28 Dec 2005
Posts: 1593
Followers: 2

Kudos [?]: 75 [0], given: 2

 [#permalink] New post 07 Jan 2006, 19:45
I would say D.

sqrt(x*y) = sqrt(x)*sqrt(y)

From statement 1, we know that root x is not an integer. Therefore, no matter what sqrt(y) turns out to be, when it gets multiplied by the value of sqrt(x), the product will not be an integer in any case.

Same logic for statement 2.

Does anyone see a flaw in this logic ? Thanks !
SVP
SVP
avatar
Joined: 14 Dec 2004
Posts: 1709
Followers: 1

Kudos [?]: 37 [0], given: 0

 [#permalink] New post 07 Jan 2006, 20:10
pmenon wrote:
I would say D.

sqrt(x*y) = sqrt(x)*sqrt(y)

From statement 1, we know that root x is not an integer. Therefore, no matter what sqrt(y) turns out to be, when it gets multiplied by the value of sqrt(x), the product will not be an integer in any case.

Same logic for statement 2.

Does anyone see a flaw in this logic ? Thanks !


Your logic will not be valid, since we don't know about "sqrt(y)". It can be an integer or non-integer that will multiply non-integer "sqrt(x)" & make result an integer or non-integer! Say for example...

what if,
sqrt(x) = 1.5 & sqrt(y)=2 ? YES, result is integer
AND
sqrt(x) = 1.5 & sqrt(y)=1.5 ? NO, result is not an integer


It should be 'E'!
SVP
SVP
avatar
Joined: 28 Dec 2005
Posts: 1593
Followers: 2

Kudos [?]: 75 [0], given: 2

 [#permalink] New post 07 Jan 2006, 20:16
vivek123 wrote:
pmenon wrote:
I would say D.

sqrt(x*y) = sqrt(x)*sqrt(y)

From statement 1, we know that root x is not an integer. Therefore, no matter what sqrt(y) turns out to be, when it gets multiplied by the value of sqrt(x), the product will not be an integer in any case.

Same logic for statement 2.

Does anyone see a flaw in this logic ? Thanks !


Your logic will not be valid, since we don't know about "sqrt(y)". It can be an integer or non-integer that will multiply non-integer "sqrt(x)" & make result an integer or non-integer! Say for example...

what if,
sqrt(x) = 1.5 & sqrt(y)=2 ? YES, result is integer
AND
sqrt(x) = 1.5 & sqrt(y)=1.5 ? NO, result is not an integer


It should be 'E'!


Vivek, in your first example, sqrt of (1.5 x 2) is still not an integer. What I am saying is that if we know already that ONE of the roots is not an integer, it wont matter if the other root comes out to an integer or not, since the root of the PRODUCT wont be an integer, and thats what the question is asking. Right ?
SVP
SVP
avatar
Joined: 28 Dec 2005
Posts: 1593
Followers: 2

Kudos [?]: 75 [0], given: 2

 [#permalink] New post 07 Jan 2006, 20:27
let me give an example. say x=3 and y=4

sqrt(xy)=sqrt(12)=sqrt(3)*sqrt(4).

Sqrt(4) is an integer, but sqrt(3) is not. Therefore, there is no way that sqrt(xy) will be an integer itself.

This comes from statement 1 when we are told that root x is not an integer.

I hope this makes sense, I really dont see it any other way :?
SVP
SVP
avatar
Joined: 14 Dec 2004
Posts: 1709
Followers: 1

Kudos [?]: 37 [0], given: 0

 [#permalink] New post 07 Jan 2006, 20:30
pmenon wrote:
vivek123 wrote:
pmenon wrote:
I would say D.

sqrt(x*y) = sqrt(x)*sqrt(y)

From statement 1, we know that root x is not an integer. Therefore, no matter what sqrt(y) turns out to be, when it gets multiplied by the value of sqrt(x), the product will not be an integer in any case.

Same logic for statement 2.

Does anyone see a flaw in this logic ? Thanks !


Your logic will not be valid, since we don't know about "sqrt(y)". It can be an integer or non-integer that will multiply non-integer "sqrt(x)" & make result an integer or non-integer! Say for example...

what if,
sqrt(x) = 1.5 & sqrt(y)=2 ? YES, result is integer
AND
sqrt(x) = 1.5 & sqrt(y)=1.5 ? NO, result is not an integer


It should be 'E'!


Vivek, in your first example, sqrt of (1.5 x 2) is still not an integer. What I am saying is that if we know already that ONE of the roots is not an integer, it wont matter if the other root comes out to an integer or not, since the root of the PRODUCT wont be an integer, and thats what the question is asking. Right ?


pmenon, I think you are mistaking it...
You are taking sqrt of (1.5 x 2) again?

I said, sqrt(x) = 1.5 & sqrt(y)=2
&
sqrt(x*y) = sqrt(x)*sqrt(y) = 1.5x2 = 3.
is this correct?
SVP
SVP
avatar
Joined: 28 Dec 2005
Posts: 1593
Followers: 2

Kudos [?]: 75 [0], given: 2

 [#permalink] New post 07 Jan 2006, 20:45
AAAAAAAAAAHHH

Sorry for the confusion folks. Vivek, youre right, for some reason i was taking the root of 3 again !!!

I change my answer to E 8-)
VP
VP
User avatar
Joined: 29 Dec 2005
Posts: 1351
Followers: 7

Kudos [?]: 28 [0], given: 0

Re: DS square rts [#permalink] New post 07 Jan 2006, 20:49
joemama142000 wrote:
Is square root of x*y an integer?
1). Root x is not an integer
2). Root y is not an integer

should be E.
from i, if x = 3 and y = 2, sqrt(xy) = is not an integer.
if x = 3 and y = 3, sqrt(xy) = is an integer.

from ii, if y = 3 and x = 2, sqrt(xy) = is not an integer.
if y = 3 and x = 3, sqrt(xy) = is an integer.

from i and ii, if x = 2, y = 3, no. if x=y=3, yes. so insuff.
Re: DS square rts   [#permalink] 07 Jan 2006, 20:49
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic Is the square root of x is an integer? sanjoo 6 07 Mar 2014, 04:54
Experts publish their posts in the topic Is the positive square root of x an integer? blackcrow 1 29 Dec 2013, 01:13
Is the positive square root of x an integer? (1) x = n^4 and ValleyBall1 1 27 Oct 2005, 15:30
Is X to the power 3 an odd integer? (1) 3 square root X is HIMALAYA 7 12 Oct 2005, 20:22
Is X to the power 3 an odd integer? (1) 3 square root X is MA 9 06 Feb 2005, 13:19
Display posts from previous: Sort by

Is square root of x*y an integer? 1). Root x is not an

  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®.