GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 20 Aug 2018, 21:11

### 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

# For which of the following functions f is f(x) = f(1-x) for

Author Message
Manager
Joined: 11 Apr 2008
Posts: 128
Location: Chicago
For which of the following functions f is f(x) = f(1-x) for  [#permalink]

### Show Tags

18 Aug 2008, 13:58
For which of the following functions f is f(x) = f(1-x) for all x?
A) f(x) = 1-x
B) f(x) =1 - (x^2)
C) f(x) = x^2 - (1-x)^2
D) f(x) = x^2 * (1-x)^2
E) f(x) = x/(1-x)

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

_________________

Factorials were someone's attempt to make math look exciting!!!

SVP
Joined: 07 Nov 2007
Posts: 1728
Location: New York

### Show Tags

18 Aug 2008, 14:02
brokerbevo wrote:
For which of the following functions f is f(x) = f(1-x) for all x?
A) f(x) = 1-x
B) f(x) =1 - (x^2)
C) f(x) = x^2 - (1-x)^2
D) f(x) = x^2 * (1-x)^2
E) f(x) = x/(1-x)

D
f(x) = x^2 * (1-x)^2
f(1-x)= (1-x)^2 * (1-(1-x))^2)=(1-x)^2 * x^2=f(x)
_________________

Smiling wins more friends than frowning

Manager
Joined: 11 Apr 2008
Posts: 128
Location: Chicago

### Show Tags

18 Aug 2008, 14:17
x2suresh wrote:
brokerbevo wrote:
For which of the following functions f is f(x) = f(1-x) for all x?
A) f(x) = 1-x
B) f(x) =1 - (x^2)
C) f(x) = x^2 - (1-x)^2
D) f(x) = x^2 * (1-x)^2
E) f(x) = x/(1-x)

D
f(x) = x^2 * (1-x)^2
f(1-x)= (1-x)^2 * (1-(1-x))^2)=(1-x)^2 * x^2=f(x)

But if x = 3 (for example)-->
f(x) ---> f(3) = 3^2 * (1-3)^2 ---> 9 * 4 = 36
f(1-x) ---> f(1-3) = -2^2 * (-2-3)^2 ---> 4 * 25 = 100

It does not work b/c 36 does not equal 100. Could someone please explain.
_________________

Factorials were someone's attempt to make math look exciting!!!

SVP
Joined: 07 Nov 2007
Posts: 1728
Location: New York

### Show Tags

18 Aug 2008, 14:29
brokerbevo wrote:
x2suresh wrote:
brokerbevo wrote:
For which of the following functions f is f(x) = f(1-x) for all x?
A) f(x) = 1-x
B) f(x) =1 - (x^2)
C) f(x) = x^2 - (1-x)^2
D) f(x) = x^2 * (1-x)^2
E) f(x) = x/(1-x)

D
f(x) = x^2 * (1-x)^2
f(1-x)= (1-x)^2 * (1-(1-x))^2)=(1-x)^2 * x^2=f(x)

But if x = 3 (for example)-->
f(x) ---> f(3) = 3^2 * (1-3)^2 ---> 9 * 4 = 36
f(1-x) ---> f(1-3) = -2^2 * (-2-3)^2 ---> 4 * 25 = 100

It does not work b/c 36 does not equal 100. Could someone please explain.

Please check the highlighted part.. you are doing wrong.

f(1-x) ---> f(1-3) =f(-2) = -2^2 * (1-(-2))^2 ---> 4 * (-3)^2 = 36
_________________

Smiling wins more friends than frowning

Manager
Joined: 11 Apr 2008
Posts: 128
Location: Chicago

### Show Tags

18 Aug 2008, 14:52
x2suresh wrote:
brokerbevo wrote:
x2suresh wrote:

But if x = 3 (for example)-->
f(x) ---> f(3) = 3^2 * (1-3)^2 ---> 9 * 4 = 36
f(1-x) ---> f(1-3) = -2^2 * (-2-3)^2 ---> 4 * 25 = 100

It does not work b/c 36 does not equal 100. Could someone please explain.

Please check the highlighted part.. you are doing wrong.

f(1-x) ---> f(1-3) =f(-2) = -2^2 * (1-(-2))^2 ---> 4 * (-3)^2 = 36

Woops. Thanks for that catch.

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

_________________

Factorials were someone's attempt to make math look exciting!!!

Re: f(x) mess &nbs [#permalink] 18 Aug 2008, 14:52
Display posts from previous: Sort by

# For which of the following functions f is f(x) = f(1-x) for

Moderator: chetan2u

# Events & Promotions

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