First consider (1) alone.
Square both sides of the equation.
(x+1)^2 = 4*(x-1)^2.
Or x^2+2x+1 = 4x^2 - 8x + 4.
Or 3x^2 - 10x + 3 = 0.
Or (3x - 1)(x - 3) = 0.
Or x = 3 or x = 1/3.
We do not get unique value of x.
So (1) alone is not sufficient.
Next consider (2) alone.
It just implies x is not equal to 3.
But we cannot say whether lxl < 1 or not.
So (2) alone is not sufficient.
Next combine both the statements together and check.
From (1) we have x = 3 or x = 1/3.
Since x is not equal to 3 by (2), x = 1/3 and lxl = 1/3 which is < 1.
So the answer to the question is yes.
The correct answer is hence (C).
DS inequality !
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
GMAT/MBA Expert
-
Rahul@gurome
- GMAT Instructor
- Posts: 1179
- Joined: Sun Apr 11, 2010 9:07 pm
- Location: Milpitas, CA
- Thanked: 447 times
- Followed by:88 members
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)
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)
-
gmatmachoman
- Legendary Member
- Posts: 2326
- Joined: Mon Jul 28, 2008 3:54 am
- Thanked: 173 times
- Followed by:2 members
- GMAT Score:710
https://www.beatthegmat.com/is-x-1-1-x-1 ... 58763.htmlsimpu wrote:wow thank you
i could not figure out that both sides of the equation had to be squared!
it seems easy now
