It is currently 26 Jun 2017, 08:34

### 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 r@s = rs + r + s, then for what value of s is r@s equal

Author Message
CEO
Joined: 21 Jan 2007
Posts: 2739
Location: New York City
If r@s = rs + r + s, then for what value of s is r@s equal [#permalink]

### Show Tags

30 May 2007, 22:07
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.

15. If r@s = rs + r + s, then for what value of s is r@s equal to r for all values of r?
(A) –1
(B) 0
(C) 1
(D) 1 / (r+1)
(E) r

i have no idea how to set this up
SVP
Joined: 01 May 2006
Posts: 1796

### Show Tags

30 May 2007, 23:38
(B) for me

we have:
o r@s = rs + r + s
and
o r@s = r

Then,
rs + r + s = r
<=> s*(r+1) = 0

So, it's s = 0 that gives us r@s = r as 0 * (r+1) = 0 for any r.
Manager
Joined: 25 May 2007
Posts: 229
Schools: Cornell
Re: PS # 15 functions [#permalink]

### Show Tags

30 May 2007, 23:54
(B)

rs + r + s = r (for all value of r)
rs + s = 0
s*(r+1) = 0
s = 0
Re: PS # 15 functions   [#permalink] 30 May 2007, 23:54
Display posts from previous: Sort by