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

Redeem

DS question

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 484
Joined: Sun Jul 30, 2006 7:01 pm
Thanked: 2 times
Followed by:1 members

DS question

by magical cook » Wed Feb 14, 2007 9:49 am
Hi

The attached question's answer is D. But I have two things that I did not understand...

1) in OG, it says √(x-5)^2 = lx-5l ,therefore, lx-5l=5-x.

But I thought, if √(x-5)^2 = 5-x, then we can make both sides squared and it will be (x-5)^2 = (5-x)^2. Can you explain why we can not both sides squared ???


2) for the first condition, -xlxl>0, but I don't get what this means....


Thanks again.
Rina :D
Attachments
DS.jpg
Top
Source: — Data Sufficiency |
Junior | Next Rank: 30 Posts
Posts: 17
Joined: Wed Jan 24, 2007 3:35 am

by amitamit2020 » Wed Feb 14, 2007 10:44 am
Rina,

Heare are my thoughts,

1) there is no inconsistancy in saying (5 - x)^2 = (X - 5)^2 it is perfectly ok .. to be more clear assume a value of X say 3, you will have 5 - x = 5 - 3 = 2 and x - 5 = 3 - 5 = -2; now squar both the things ou will get (2^2) = ((-2)^2) = 4

2) -x * |x| > 0 means that x < 0 because we have |x| which is always positive or zero. Now that means - x has to be positive in order to satisfy the given condition. so x is negative i.e. x < 0

for the given question X < 0 < 5 means that x - 5 < 0

now |X - 5| = - (x - 5) .. if (x-5 < 0 ... (from definition of mode)

so |x - 5 | = 5 - x .. thus statement (2) alone is also sufficinet to answer the question.

Hope it clarifies.
Top
Post new topic Post Reply
• Page 1 of 1