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Is x > 0?

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Is x > 0?

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Is x > 0?

(1) x^2 > 0
(2) x + 2 > 0

OA=E

Source: Manhattan GMAT

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VJesus12 wrote:
Is x > 0?

(1) x² > 0
(2) x + 2 > 0
Target question: Is x > 0?

Statement 1: x² > 0
This statement doesn't feel sufficient, so I'll TEST some values.
There are several values of x that satisfy statement 1. Here are two:
Case a: x = 1. In this case, the answer to the target question is YES, it is the case that x > 0
Case b: x = -1. In this case, the answer to the target question is NO, it is NOT the case that x > 0
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: x + 2 > 0
There are several values of x that satisfy statement 2. Here are two:
Case a: x = 1. In this case, the answer to the target question is YES, it is the case that x > 0
Case b: x = -1. In this case, the answer to the target question is NO, it is NOT the case that x > 0
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
IMPORTANT: Notice that I was able to use the same counter-examples to show that each statement ALONE is not sufficient.
So, the same counter-examples will satisfy the two statements COMBINED.
In other words,
Case a: x = 1. In this case, the answer to the target question is YES, it is the case that x > 0
Case b: x = -1. In this case, the answer to the target question is NO, it is NOT the case that x > 0
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent

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Brent Hanneson – Creator of GMATPrepNow.com
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