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

Redeem

Krish PS - 1

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 5
Joined: Thu Jun 26, 2008 4:23 pm

Krish PS - 1

by KrishMBA » Mon Dec 29, 2008 7:53 pm
Hi,

For which of the following is f(x) = f(1-x) for all x ?

Choices are:

1. f(x) = 1-x
2. f(x) = 1-x^2
3. f(x) = x^2 - (1-x)^2
4. f(x) = x^2(1-x)^2
5. f(x) = x / 1-x


The answer is choice 4 but could someone please explain the solution ?

Thanks,
Krish
Top
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 37
Joined: Wed Sep 17, 2008 8:17 pm
Location: India
Thanked: 4 times

Re: Krish PS - 1

by Sachindh » Mon Dec 29, 2008 7:57 pm
KrishMBA wrote:Hi,

For which of the following is f(x) = f(1-x) for all x ?

Choices are:

1. f(x) = 1-x
2. f(x) = 1-x^2
3. f(x) = x^2 - (1-x)^2
4. f(x) = x^2(1-x)^2
5. f(x) = x / 1-x


The answer is choice 4 but could someone please explain the solution ?

Thanks,
Krish
A simple way is to replace the 'x with (1-x) and the value of f(x) should not change.
So, If you look at the options only 4 is that which does not change if I change x by (1-x).

I hope it helps.
Thanks
Top
Newbie | Next Rank: 10 Posts
Posts: 5
Joined: Thu Jun 26, 2008 4:23 pm

by KrishMBA » Mon Dec 29, 2008 8:11 pm
Hi Sachin,

Thanks for your reply... But could you please provide an example or show how option 4 is correct ...
Top
Senior | Next Rank: 100 Posts
Posts: 37
Joined: Wed Sep 17, 2008 8:17 pm
Location: India
Thanked: 4 times

by Sachindh » Mon Dec 29, 2008 8:17 pm
KrishMBA wrote:Hi Sachin,

Thanks for your reply... But could you please provide an example or show how option 4 is correct ...
Take option 4
f(x) = x^2(1-x)^2
f(1-x) = (1-x)^2(1-(1-x))^2
f(1-x) = (1-x)^2 (1-1+x)^2
f(1-x) = (1-x)^2 (0+x)^2
f(1-x) = f(x)

Now in other cases this shall not be true.

Thanks
Top
Newbie | Next Rank: 10 Posts
Posts: 5
Joined: Thu Jun 26, 2008 4:23 pm

by KrishMBA » Mon Dec 29, 2008 8:59 pm
Thanks Sachin !
Top
Post new topic Post Reply
• Page 1 of 1