BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Don't force

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

Don't force

by sanju09 » Mon Sep 13, 2010 4:00 am
For which of the following functions 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)


[spoiler]Source: Don't force[/spoiler]
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 1179
Joined: Sun Apr 11, 2010 9:07 pm
Location: Milpitas, CA
Thanked: 447 times
Followed by:88 members

by Rahul@gurome » Mon Sep 13, 2010 4:17 am
Best approach is to start from the last choice. So, start from option (E).
(E) f(1 - x) = (1 - x)/[1 - (1 - x)] = (1 - x)/x, which is not equal to f(x).

(D) f(1 - x) = (1 - x)^2 * [1 - (1 - x)]^2 = (1 - x)^2*(x^2), which is the same as f(x).

The correct answer is [spoiler](D)[/spoiler].
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 146
Joined: Fri Jun 25, 2010 3:42 am
Thanked: 3 times
Followed by:1 members
GMAT Score:560

by alivapriyada » Mon Sep 13, 2010 4:28 am
For which of the following functions 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)
The same question i got in my prep. And even I answered it correctly in the exam.

Lets start from answer option A
F(x)= 1-x
F(1-x) = 1-(1-x) =-x
eliminate A

come to B
F(x)=1-x^2
F(1-x)= 1-(1-x)^2 =1-(1+x^2-2x)
seems complicated?? we can eliminate this option.

come to C
F(x)=x^2-(1-x)^2
F(1-x)=(1-x)^2-(1-1+x)^2
=(1-x)^2-X^2
not equal
Eliminate C

come to D
F(x)=x^2(1-x)^2
F(1-x)=(1-x)^2 (1-1+x)^2
=(1-x)^2(x)^2
where F(x)=F(1-x)
hence the answer is D
Top
Post new topic Post Reply
• Page 1 of 1