R and M are positive even numbers. Is root (R*M) a positive : DS Archive
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 24 Jan 2017, 03:16

### 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

# R and M are positive even numbers. Is root (R*M) a positive

Author Message
Senior Manager
Joined: 15 Aug 2004
Posts: 329
Followers: 1

Kudos [?]: 8 [0], given: 0

R and M are positive even numbers. Is root (R*M) a positive [#permalink]

### Show Tags

06 Sep 2006, 01:35
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

R and M are positive even numbers. Is root (R*M) a positive integer?

1) (root R + root M) is positive even integer.

2) Root R is a positive even integer.

Senior Manager
Joined: 11 May 2006
Posts: 258
Followers: 2

Kudos [?]: 23 [0], given: 0

### Show Tags

06 Sep 2006, 02:04
sumitsarkar82 wrote:
R and M are positive even numbers. Is root (R*M) a positive integer?

1) (root R + root M) is positive even integer.

2) Root R is a positive even integer.

I pick A

1) says r^1/2 + m^1/2 = 2k for some k

=> r + m + 2(rm)^1/2 = 4k^2
=> 2(rm)^1/2 = 4k^2 -r -m

now RHS should be even as 4k is even, r is even and m is even

=> (rm)^1/2 should be a positive integer.
so sufficient.

2) does not say anthing about m so insufficient.
Senior Manager
Joined: 15 Aug 2004
Posts: 329
Followers: 1

Kudos [?]: 8 [0], given: 0

### Show Tags

06 Sep 2006, 02:09
iced_tea wrote:
I pick A

1) says r^1/2 + m^1/2 = 2k for some k

=> r + m + 2(rm)^1/2 = 4k^2
=> 2(rm)^1/2 = 4k^2 -r -m

now RHS should be even as 4k is even, r is even and m is even

=> (rm)^1/2 should be a positive integer.
so sufficient.

What if

a) R = 16, M =4
root R could be 4, root M could be -2

b) R = 16, M =4
root R could be 4, root M could be 2

Satisfies (root R + root M) is positive even integer. But root (R*M) could be +v2 or -ve
Re: DS - R&M   [#permalink] 06 Sep 2006, 02:09
Display posts from previous: Sort by