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

 It is currently 27 Oct 2016, 06:21

### 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

# Functions question from GMATclub m25

Author Message
TAGS:

### Hide Tags

Manager
Joined: 04 Sep 2009
Posts: 52
WE 1: Real estate investment consulting
Followers: 2

Kudos [?]: 22 [0], given: 7

Functions question from GMATclub m25 [#permalink]

### Show Tags

29 Sep 2009, 09:12
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 100% (02:50) wrong based on 3 sessions

### HideShow timer Statistics

Guys, need your help on understanding this one - comes from GMAT Club test m25 Q22. Have not found it via search. Would love to get a thorough explanation. Thanks!

If function f(x) satisfies $$f(x)=f(x^2)$$ for all x, which of the following must be true?

A. f(4)=f(2)f(2)
B. f(16)-f(-2)=0
C. f(-2)+f(4)=0
D. f(3)=3f(3)
E. f(0)=0

The OA is here
[Reveal] Spoiler:
B. f(-2)=f(2)=f(4)=f(16). The other choices are not necessarily true. Consider f(x)=3 for all x.
Manager
Joined: 15 Sep 2009
Posts: 137
Followers: 1

Kudos [?]: 22 [0], given: 2

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

29 Sep 2009, 09:32
f(2) = f(4) = f(16)

so option B is correct
Manager
Joined: 04 Sep 2009
Posts: 52
WE 1: Real estate investment consulting
Followers: 2

Kudos [?]: 22 [0], given: 7

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

29 Sep 2009, 09:58
I know the answer, thank you

What I need is the logic behind it and why the other options are not correct.
Manager
Joined: 14 Dec 2008
Posts: 169
Followers: 1

Kudos [?]: 22 [0], given: 39

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

29 Sep 2009, 10:15
Well at first go, even i had no idea, just trying to understand.
Everything is defined in term of functions, and function can be defined in any way
like it can be
f(X) = ax+b or \sqrt{x}, so its only become true for B, its kind of weird that, in B we are keep on substituting for second function and keeping first part as it is, i think it can be only B which can equate to RHS and no other option is possible/true.
Manager
Joined: 14 Dec 2008
Posts: 169
Followers: 1

Kudos [?]: 22 [0], given: 39

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

29 Sep 2009, 10:19
even E looks true, but remember its a function in general. so it cannot be true. Only B, once you substitute F(16) for F(-2) ; F(16) - F(16) = 0
Manager
Joined: 04 Sep 2009
Posts: 52
WE 1: Real estate investment consulting
Followers: 2

Kudos [?]: 22 [0], given: 7

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

29 Sep 2009, 10:55
manojgmat wrote:
even E looks true, but remember its a function in general. so it cannot be true.

Thanks for trying to explain! What did you mean by the above? I actually picked this answer as it seemed less complicated to me.

This is the question where I get quite lost so far...
Manager
Joined: 14 Dec 2008
Posts: 169
Followers: 1

Kudos [?]: 22 [0], given: 39

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

29 Sep 2009, 12:07
Just forget it, incase u have not picked E too..
Manager
Joined: 04 Sep 2009
Posts: 52
WE 1: Real estate investment consulting
Followers: 2

Kudos [?]: 22 [0], given: 7

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

29 Sep 2009, 13:21
That's exactly what I picked although did look a bit suspicious
Intern
Joined: 17 Jan 2010
Posts: 30
Followers: 0

Kudos [?]: 21 [0], given: 8

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

23 Jan 2010, 01:25
i'm totally lost on this one. could someone please explain the solution to this question?
Manager
Joined: 26 Nov 2009
Posts: 175
Followers: 3

Kudos [?]: 56 [0], given: 5

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

23 Jan 2010, 11:10
b)f(16)-f(-2)=0

if the ans is b by substituting f(-2)=f(4)=f(16)

u can also have f(16)=f(256) and so on..

the question asks which ans choice is correct for all x

I am still not convinced there must be some better expalantion

Last edited by silasaaa2 on 23 Jan 2010, 11:11, edited 1 time in total.
Manager
Joined: 26 Nov 2009
Posts: 175
Followers: 3

Kudos [?]: 56 [0], given: 5

Re: Functions question from GMATclub m25 [#permalink]

### Show Tags

23 Jan 2010, 11:10
but i am against choice E as well as the question says for all x.

choice E will hold gold only if x is zero not for other values of x
Re: Functions question from GMATclub m25   [#permalink] 23 Jan 2010, 11:10
Similar topics Replies Last post
Similar
Topics:
13 Fractions Question From GMAT Club Test (m25#15) 7 08 May 2011, 00:27
Function question 4 16 Nov 2011, 23:58
2 Functions question 2 16 Oct 2011, 01:26
Cylinder Tank Capacity - GMATClub Test m25 q#37 7 10 Aug 2011, 23:47
Prep Question - function 1 04 Jan 2010, 17:44
Display posts from previous: Sort by