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

It is currently 25 Jun 2016, 23:52
GMAT Club Tests

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

For which of the following functions is f(a+b) = f(a) + f(b)

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Intern
Intern
avatar
Joined: 01 Aug 2007
Posts: 31
Followers: 0

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

For which of the following functions is f(a+b) = f(a) + f(b) [#permalink]

Show Tags

New post 31 Aug 2007, 10:20
For which of the following functions is f(a+b) = f(a) + f(b) for all positive numbers a and b?

a) f(x) = x^2
b) f(x) = x+1
c) f(x) = x^(1/2)
d) f(x) = 2/x
e) f(x) = -3x

*It would be greatly appreciated if you could provide step-by-step approach to solving this one
VP
VP
avatar
Joined: 10 Jun 2007
Posts: 1459
Followers: 7

Kudos [?]: 208 [0], given: 0

Re: Functions - GMATPrep [#permalink]

Show Tags

New post 31 Aug 2007, 10:37
jp888 wrote:
For which of the following functions is f(a+b) = f(a) + f(b) for all positive numbers a and b?

a) f(x) = x^2
b) f(x) = x+1
c) f(x) = x^(1/2)
d) f(x) = 2/x
e) f(x) = -3x

*It would be greatly appreciated if you could provide step-by-step approach to solving this one


E

Pick a number, then plug in
Set x = 3 = 1+2

f(3):f(1):f(2):f(1)+f(2)

A) 9:1:4:5
B) 4:2:3:5
C) sqrt(3):1:sqrt(2):sqrt(2)+1
D) 2/3:2:1:3
E) -9:-3:-6:-9

E is correct.
Intern
Intern
avatar
Joined: 05 Jul 2007
Posts: 4
Followers: 0

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

 [#permalink]

Show Tags

New post 01 Sep 2007, 04:46
E

f(x) = -3x
f(y) = - 3x
f(x) + f(y) = -3x - 3y

f(x+y) = -3(x+y) = -3x - 3y

So f(x)+f(y) = f(x+y)
Manager
Manager
avatar
Status: I will not stop until i realise my goal which is my dream too
Joined: 25 Feb 2010
Posts: 235
Schools: Johnson '15
Followers: 2

Kudos [?]: 48 [0], given: 16

Re: Functions - GMATPrep [#permalink]

Show Tags

New post 03 Jul 2011, 00:36
i dont think so i understood why the answer is to be E

the question says that the function given in the 1st line is only for positive numbers and all the 4 options work for that...but it has clearly said that it wont work for negative numbers, hence E should be the one?

Can someone please explain the reasons for choosing E as the answer...
_________________

Regards,
Harsha

Note: Give me kudos if my approach is right , else help me understand where i am missing.. I want to bell the GMAT Cat ;)

Satyameva Jayate - Truth alone triumphs

Re: Functions - GMATPrep   [#permalink] 03 Jul 2011, 00:36
    Similar topics Author Replies Last post
Similar
Topics:
Experts publish their posts in the topic Which of the following is equal to the cube of a non-integer? marshallbrm 2 03 Dec 2014, 18:23
1 Experts publish their posts in the topic quadratic function iwill 3 27 Feb 2014, 04:45
1 Function question danzig 0 21 Jul 2013, 16:22
18 Experts publish their posts in the topic If x is an even integer, which of the following must be an slsu 14 10 Oct 2007, 00:08
For which of the following function f is f(x) = f(1-x) for Hang Tuah 3 23 Dec 2007, 22:17
Display posts from previous: Sort by

For which of the following functions is f(a+b) = f(a) + f(b)

  new topic 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 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®.