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What is the value of x?

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Source: — Data Sufficiency |

by chidcguy » Mon May 26, 2008 2:28 pm
1) (-x)^3 = -x^3

-x X -x X -x = -x^3

which means -x^3 = -x^3, means x^3 = x^3 x can be 0, 1, 2, -1 for that matter any value of X will satisfy. No sufficiency

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

-x X -x = -x^2

x^2 = -x^2 means 2 x^2=0 means x^2=0 means x=0

B is sufficient

Is OA B? or Did I miss some thing?
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by VP_Tatiana » Mon May 26, 2008 2:30 pm
The answer to this question would be B.

Statement (1) is essentially an identity. It holds true for any value of x. I'll prove it.

(-x)^3 = -x^3 can be expressed as

((-1)^3) * (x^3) = -x^3. Simplifying, we have

-x^3 = -x^3, which is true for any value of x.

Statement (2), on the other hand, can only be satisfied when x is 0.

(-x) ^ 2 = -x^2 can be expressed as

((-1)^2) * (x^2) = -x^2. Simplifying, we have

x^2 = -x^2.

This is only true if x = 0, so statement (2) alone is sufficient to solve for x. So, the answer is B.
Tatiana Becker | GMAT Instructor | Veritas Prep
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