Inequalities

This topic has expert replies
Source: — Data Sufficiency |

User avatar
Legendary Member
Posts: 1275
Joined: Thu Sep 21, 2006 11:13 pm
Location: Arabian Sea
Thanked: 125 times
Followed by:2 members

by ajith » Fri Jan 22, 2010 6:55 am
rahul.s wrote:Is |x| + |x - 1| = 1?

1) x => 0
2) x <= 1
Consider 3 cases

a) if x is greater than one

|x| + |x - 1| is not equal to one (it is greater)

b) if x is less than zero then

|x| + |x - 1| is not equal to one (it is greater)

c) Now if x is in between 1 and 0 (both included)

|x| + |x - 1| is equal to 1

since 1 and 2 both together gives condition 'c'

both statements together are enough to validate the claim

[ Get to the boundary conditions of the sign change (of the absolute function) and evaluate each segment in the number line ]
Always borrow money from a pessimist, he doesn't expect to be paid back.

Master | Next Rank: 500 Posts
Posts: 324
Joined: Thu Dec 24, 2009 6:29 am
Thanked: 17 times
Followed by:1 members

by rahul.s » Fri Jan 22, 2010 7:23 am
You're right, the OA's C