Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

It is currently 21 Jul 2019, 20:43

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.

Close

Request Expert Reply

Confirm Cancel

For which of the following functions does f(x)=f(2-x)?

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

Hide Tags

Find Similar Topics 
Manager
Manager
avatar
Joined: 01 Jul 2012
Posts: 81
Location: United States
GMAT 1: 510 Q34 V28
GMAT 2: 580 Q35 V35
GMAT 3: 640 Q34 V44
GMAT 4: 690 Q43 V42
GPA: 3.61
WE: Education (Education)
For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 11 Jul 2013, 10:06
2
12
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

65% (01:35) correct 35% (01:53) wrong based on 533 sessions

HideShow timer Statistics


For which of the following functions does f(x)=f(2-x)?

A. f(x)=x+2
B. (fx)=2x-x^2
C. f(x)=2-x
D. f(x)=(2-x)^2
E. f(x)=x^2

Answer choice C seems to work out if we plug in 1 for x. Did I do something wrong or must the function be true for all values? C does not work for a value of x=4?
f(x)=2-1=1
f(x)= 2-(2-x).....>2-(2-1).....>2-(1) = 1
Most Helpful Community Reply
Director
Director
User avatar
Joined: 14 Dec 2012
Posts: 736
Location: India
Concentration: General Management, Operations
GMAT 1: 700 Q50 V34
GPA: 3.6
GMAT ToolKit User
Re: For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 11 Jul 2013, 10:17
5
3
josemnz83 wrote:
For which of the following functions does f(x)=f(2-x)?

A. f(x)=x+2
B. (fx)=2x-x^2
C. f(x)=2-x
D. f(x)=(2-x)^2
E. f(x)=x^2

Answer choice C seems to work out if we plug in 1 for x. Did I do something wrong or must the function be true for all values? C does not work for a value of x=4?
f(x)=2-1=1
f(x)= 2-(2-x).....>2-(2-1).....>2-(1) = 1


hi,

in all the option just put 2-x in place of x

A. f(x)=x+2===>f(2-x)=2-x+2=4-x==>not equal

B. (fx)=2x-x^2====>f(2-x)=2(2-x)-(2-x)^2=4-2x-x^2+4x-4=2x-x^2===>equal==correct

C. f(x)=2-x===>f(2-x)=2-(2-x)=x===>not equal

D. f(x)=(2-x)^2===>f(2-x)=(2-2+x)^2=x^2===>not equal

E. f(x)=x^2===>f(2-x)=(2-x)^2===>not equal

hence only B satisfies.

dont plug in this

hope it helps.
_________________
When you want to succeed as bad as you want to breathe ...then you will be successfull....

GIVE VALUE TO OFFICIAL QUESTIONS...



GMAT RCs VOCABULARY LIST: http://gmatclub.com/forum/vocabulary-list-for-gmat-reading-comprehension-155228.html
learn AWA writing techniques while watching video : http://www.gmatprepnow.com/module/gmat-analytical-writing-assessment
: http://www.youtube.com/watch?v=APt9ITygGss
General Discussion
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 56307
Re: For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 11 Jul 2013, 10:20
1
josemnz83 wrote:
For which of the following functions does f(x)=f(2-x)?

A. f(x)=x+2
B. (fx)=2x-x^2
C. f(x)=2-x
D. f(x)=(2-x)^2
E. f(x)=x^2

Answer choice C seems to work out if we plug in 1 for x. Did I do something wrong or must the function be true for all values? C does not work for a value of x=4?
f(x)=2-1=1
f(x)= 2-(2-x).....>2-(2-1).....>2-(1) = 1


If you plug x=1 then all options will work, since f(x)=f(1) and f(2-x)=f(1) too. For such kind of questions it's not a good idea to plug 0, -1 or 1.

Note that for plug-in method it might happen that for some particular number(s) more than one option may give "correct" answer. In this case just pick some other numbers and check again these "correct" options only.

Similar questions:
functions-problem-need-help-93184.html
for-which-of-the-following-functions-is-f-a-b-f-b-f-a-124491.html
let-the-function-g-a-b-f-a-f-b-143311.html
for-which-of-the-following-functions-f-is-f-x-f-1-x-for-85751.html

Hope it helps.
_________________
Manager
Manager
avatar
Joined: 24 May 2013
Posts: 79
GMAT ToolKit User
Re: For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 11 Jul 2013, 10:54
josemnz83 wrote:
For which of the following functions does f(x)=f(2-x)?

A. f(x)=x+2
B. (fx)=2x-x^2
C. f(x)=2-x
D. f(x)=(2-x)^2
E. f(x)=x^2

Answer choice C seems to work out if we plug in 1 for x. Did I do something wrong or must the function be true for all values? C does not work for a value of x=4?
f(x)=2-1=1
f(x)= 2-(2-x).....>2-(2-1).....>2-(1) = 1


If we plug x=0 then, f(0)=f(2)
A. F(0)= 2 and f(2)= 4
B. f(0)= 0 and f(2)= 0
C. F(0)= 2 and f(2)= 0
D. F(0)= 4 and f(2)= 0
E. f(0)= 0 and f(2)= 4

Hence b is the correct answer.
Manager
Manager
User avatar
Joined: 08 Nov 2014
Posts: 80
Location: India
GPA: 3
WE: Engineering (Manufacturing)
GMAT ToolKit User
Re: For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 22 Dec 2014, 10:50
1
It can be easily done in less than a minute simply by elimination or substitution method.

1) f(x)=x+2; for x=2-x , f(2-x)=4. Eliminated
2) f(x) = 2x-x^2; for x=2-x ,f(2-x)=2(2-x)-(2-x)^2 =(2-x)(2-2+x)=2x-x^2
3) f(x) = 2 - x; for x=2-x, f(2-x)=x . Eliminated
4) f(x)=(2-x)^2; for x=2-x, f(2-x)=(x)^2 . Eliminated
5) f(x)=x^2;for x=2-x, f(2-x)=(2-x)^2. Eliminated
_________________
"Arise, Awake and Stop not till the goal is reached"
Director
Director
avatar
S
Joined: 12 Nov 2016
Posts: 713
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
GPA: 2.66
Re: For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 23 Feb 2017, 19:34
What confuses my about this question, with answer "B," is an example in which you have f(2-3)

f(2-3)=-1

F(x)= 2(2-x)-(2-x)^2
F(2-3)= 2(2-3)-(2-3)^2
F(2-3)= 2(-1)-(-1)^2
F(2-3)= -2-1
F(2-3)= -3?

Maybe I'm tired or something but I keep coming to this conclusion.
Manager
Manager
avatar
B
Joined: 31 Dec 2016
Posts: 70
For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 18 Jul 2017, 17:01
1
Nunuboy1994 wrote:
What confuses my about this question, with answer "B," is an example in which you have f(2-3)

f(2-3)=-1

F(x)= 2(2-x)-(2-x)^2
F(2-3)= 2(2-3)-(2-3)^2
F(2-3)= 2(-1)-(-1)^2
F(2-3)= -2-1
F(2-3)= -3?

Maybe I'm tired or something but I keep coming to this conclusion.


A good way to solve it is like this. Essentially the question is saying F(X) so everytime you see an X you're going to sub in the function 2-x. A good video explaining how functions work is here since most people here do a crappy job. https://www.youtube.com/watch?v=T6-Zdr5w_bE
Attachments

Function question 3.png
Function question 3.png [ 292.42 KiB | Viewed 29694 times ]

Senior Manager
Senior Manager
User avatar
G
Status: love the club...
Joined: 24 Mar 2015
Posts: 274
Re: For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 11 Oct 2017, 13:59
josemnz83 wrote:
For which of the following functions does f(x)=f(2-x)?

A. f(x)=x+2
B. (fx)=2x-x^2
C. f(x)=2-x
D. f(x)=(2-x)^2
E. f(x)=x^2

Answer choice C seems to work out if we plug in 1 for x. Did I do something wrong or must the function be true for all values? C does not work for a value of x=4?
f(x)=2-1=1
f(x)= 2-(2-x).....>2-(2-1).....>2-(1) = 1



hi

let f(0) = f(2)

B: f(0) = 0
f(2) = 4 - 4 = 0

so f(0)= f(2)
B is the answer

thanks
VP
VP
avatar
G
Joined: 09 Mar 2018
Posts: 1002
Location: India
Re: For which of the following functions does f(x)=f(2-x)?  [#permalink]

Show Tags

New post 11 Jan 2019, 22:03
1
josemnz83 wrote:
For which of the following functions does f(x)=f(2-x)?

A. f(x)=x+2
B. (fx)=2x-x^2
C. f(x)=2-x
D. f(x)=(2-x)^2
E. f(x)=x^2


A. f(x)=x+2
f(2-x) = 2-x+2, Not equal

B. f(x)=2x-x^2
f(2-x) = 2*(2-x) - (2-x)^2 = 4-2x- [ 4 + x^2 - 4x] = 2x-x^2

C. f(x)=2-x
f(2-x) = 2-2+x = x, Not equal

D. f(x)=(2-x)^2
f(2-x)= (2-2-x)^2 , Not equal

E. f(x)=x^2
f(2-x) = (2-x)^2, Not equal

Answer B
_________________
If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.
GMAT Club Bot
Re: For which of the following functions does f(x)=f(2-x)?   [#permalink] 11 Jan 2019, 22:03
Display posts from previous: Sort by

For which of the following functions does f(x)=f(2-x)?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne