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

 It is currently 06 May 2015, 22:16

### 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

# PS- GMAT Prep

Author Message
TAGS:
Intern
Joined: 21 Apr 2006
Posts: 18
Location: San Francisco, CA
Followers: 0

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

PS- GMAT Prep [#permalink]  21 Jun 2006, 21:36
00:00

Difficulty:

(N/A)

Question Stats:

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

math_02.gif [ 15.52 KiB | Viewed 527 times ]

Manager
Joined: 01 Jun 2006
Posts: 141
Followers: 1

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

We have f(x)=-3x
so f(a)+f(b)=-3a-3b=-3*(a+b)=f(a+b)
VP
Joined: 15 Jun 2006
Posts: 1124
Schools: Chicago Booth
Followers: 4

Kudos [?]: 40 [0], given: 0

f(a+b)=f(a)+f(b) is true only for multiplication
therefore only the last is true f(x)=-3x
Intern
Joined: 21 Apr 2006
Posts: 18
Location: San Francisco, CA
Followers: 0

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

duh! Thank you folks!

-Tru
VP
Joined: 02 Jun 2006
Posts: 1267
Followers: 2

Kudos [?]: 42 [0], given: 0

Clearly E.

-3(a+b) = -3a + (-3b)
f(a+b) = f(a) + f(b)
Director
Joined: 06 May 2006
Posts: 781
Followers: 3

Kudos [?]: 16 [0], given: 0

Yup. E.

Hey, if you don't mind my asking, how much did you score on that test? Just curious...
VP
Joined: 25 Nov 2004
Posts: 1495
Followers: 6

Kudos [?]: 38 [0], given: 0

Re: PS- GMAT Prep [#permalink]  22 Jun 2006, 17:01
guys, i am dumb on this one. i like to know every step on this one.
thankx..
VP
Joined: 02 Jun 2006
Posts: 1267
Followers: 2

Kudos [?]: 42 [0], given: 0

Re: PS- GMAT Prep [#permalink]  22 Jun 2006, 17:32
For given functions A..E we need one which is such that
f(a+b) = f(a) + f(b)

A. f(x) = x^2 i.e. f(a+b) = (a+b)^2
This is not equal to a^2 + b^2 = f(a) + f(b)

B. f(x) = x+1
f(a+b) = a+b+1
f(a) + f(b) = a+1 + b+1 = a+b+2 which is not eq. f(a+b)

C. f(x) = sqrt(x)
f(a+b) = sqrt(a+b) which is not eq. sqrt(a) + sqrt(b)

D. f(x) = 2/x
f(a+b) = 2/(a+b) which is not eq to 2/a + 2/b

E. f(x) = -3x
f(a+b) = -3(a+b) = -3a + (-3b) = f(a) + f(b). Equal.

Therefore E.

MA wrote:
guys, i am dumb on this one. i like to know every step on this one.
thankx..
VP
Joined: 25 Nov 2004
Posts: 1495
Followers: 6

Kudos [?]: 38 [0], given: 0

Re: PS- GMAT Prep [#permalink]  22 Jun 2006, 18:18
great. you guys are ginious.

now its pretty clear. thanx a ton again.

haas_mba07 wrote:
For given functions A..E we need one which is such that
f(a+b) = f(a) + f(b)

A. f(x) = x^2 i.e. f(a+b) = (a+b)^2
This is not equal to a^2 + b^2 = f(a) + f(b)

B. f(x) = x+1
f(a+b) = a+b+1
f(a) + f(b) = a+1 + b+1 = a+b+2 which is not eq. f(a+b)

C. f(x) = sqrt(x)
f(a+b) = sqrt(a+b) which is not eq. sqrt(a) + sqrt(b)

D. f(x) = 2/x
f(a+b) = 2/(a+b) which is not eq to 2/a + 2/b

E. f(x) = -3x
f(a+b) = -3(a+b) = -3a + (-3b) = f(a) + f(b). Equal.

Therefore E.
Re: PS- GMAT Prep   [#permalink] 22 Jun 2006, 18:18
Similar topics Replies Last post
Similar
Topics:
PS- GMAT Prep 7 21 Jun 2006, 21:34
GMAT Prep PS - Geometry 5 11 Jun 2006, 18:09
PS- x (GMAT Prep) 4 31 May 2006, 01:37
PS-GMAT prep 9 23 Feb 2006, 15:25
PS-GMAT prep 3 23 Feb 2006, 15:12
Display posts from previous: Sort by