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B
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Difficulty:
15%
(low)
Question Stats:
72% (01:00) correct
28%
(01:10)
wrong
based on 812
sessions
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What is the value of x?
(1) \(x^3 - x^2 = 0\)
(2) \((-x)^2 = -x^2\)
(1) \(x^3 - x^2 = 0\)
(2) \((-x)^2 = -x^2\)
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18 Dec 2012, 23:34
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jsphcal
1) x can be either 0 or 1. Insufficient.
2) Lets say \(x^2 = a\). We are given a = -a. So, a can only be 0 and hence x can only be 0.
Answer is B
19 Dec 2012, 02:39
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jsphcal
In this case, it is better to simplify. This is a "value" question, so our answer depends on finding the exact value of x.
(1)
\(x^3-x^2=0\)
\(x^2(x-1)=0\)
=> either x=0 or x=1
INSUFFICIENT
(2)
\((-x)^2 = -x^2\)
Simplifying left hand side,
\((-x)^2 = (-1*x)^2 = (-1)^2 * (x)^2 = x^2\)
Thus the original expression is reduced to \(x^2=-x^2\), which can only happen when x=0.
SUFFICIENT
Thus the answer is B.
