Please help function problem

Expert replies

angela22: Newbie | Next Rank: 10 Posts; Posts: 7; Joined: Fri Apr 04, 2008 3:16 pm

by angela22 » Fri Apr 04, 2008 4:08 pm

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) = 1/(1-x)

Thanks so much!

Like this post

Source: Beat The GMAT — Problem Solving | Fri Apr 04, 2008 4:08 pm

lagomez: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Thu Feb 14, 2008 9:06 am; Thanked: 1 times

by lagomez » Sat Apr 05, 2008 8:29 am

i used numbers

if i use x = 3 then

f(3) = f(1-x) or f(3) = (-2)

then i go through each question by doing:

a) f(x) = (1-x)
(1-3) = (1-(-2))
(-2) = (3) so this is wrong

i work may way down until d comes up
f(x) = x^2(1-x)^2

3^2(1-3)^2 = -2^2(1-(-2))^2
9(4) = 4(9)

this should work for any number you choose

so answer is D

Like this post

angela22: Newbie | Next Rank: 10 Posts; Posts: 7; Joined: Fri Apr 04, 2008 3:16 pm

by angela22 » Sat Apr 05, 2008 5:19 pm

thank you! functions has always been a weakness of mine! =) but just to make sure....this is what you did right??

set x=3 and plug it into the given function f(x)=f(1-x) which gives you:
f(3)=f(-2)

and then for all the answer choices you plugged in x=3 on one side and x=-2 for the other side and see which one is equal??

Like this post

lagomez: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Thu Feb 14, 2008 9:06 am; Thanked: 1 times

by lagomez » Sat Apr 05, 2008 8:20 pm

that is correct..try for any number x

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review