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What is the value of x?

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What is the value of x?  [#permalink]

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New post Updated on: 19 Dec 2012, 08:12
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A
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Question Stats:

69% (00:43) correct 31% (00:57) wrong based on 154 sessions

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What is the value of x?

(1) \(x^3 - x^2 = 0\)
(2) \((-x)^2 = -x^2\)

Originally posted by jsphcal on 18 Dec 2012, 22:59.
Last edited by jsphcal on 19 Dec 2012, 08:12, edited 1 time in total.
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Re: What is the value of x?  [#permalink]

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New post 18 Dec 2012, 23:34
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jsphcal wrote:
What is the value of x?

(1) x^3 - x^2 = 0

(2) (-x)^2 = -x^2


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
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Re: What is the value of x?  [#permalink]

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New post 19 Dec 2012, 02:39
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jsphcal wrote:
What is the value of x?

(1) x^3 - x^2 = 0

(2) (-x)^2 = -x^2


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.
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Re: What is the value of x?  [#permalink]

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New post 19 Dec 2012, 02:44
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New post 25 Jul 2018, 10:38
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Re: What is the value of x? &nbs [#permalink] 25 Jul 2018, 10:38
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