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Inequalities

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Inequalities

by rahul.s » Mon Jan 11, 2010 8:36 am
Is |x| < 1?

1) |x +1| = 2|x - 1|

2) |x - 3| not = 0

This problem seemed easy to me. I guess I messed up the approach.

Source: Old Practice Test

OA is C
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Source: — Data Sufficiency |
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by papgust » Mon Jan 11, 2010 7:27 pm
-1 < x > 1?

1. |x +1| = 2|x - 1|

Squaring both sides,

(x+1)^2 = 4 * (x-1)^2
x2 + 2x + 1 = 4x2 - 8x + 4
3x2 - 10x + 3 = 0
x = 3, 1/3
Insufficient.

2. |x - 3| <> 0
x <> 3
Insufficient.

Combined,
x = 1/3. Lies b/w -1 and 1.
Sufficient.
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