Inequlaities

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Source: — Data Sufficiency |

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by Anurag@Gurome » Tue Jul 19, 2011 9:40 pm
joinn wrote:Is X > K ?

1) 2x * 2k = 4
2) 9x * 3k = 81

Please anyone explain in detail ...
I think the question is not correct as the two statements are contradicting each other. From statement 1 we get xk = 1 and from statement 2 we get xk = 3. But in GMAT DS question, the statements never contradict each other.

I guess the question is as below:

Is x > k ?

1) 2^x * 2^k = 4
2) 9^x * 3^k = 81

(1) 2^x * 2^k = 4 implies 2^(x + k) = 2^2 implies x + k = 2; NOT sufficient.

(2) 9^x * 3^k = 81 implies 3^(2x + k) = 3^4 implies 2x + k = 4; NOT sufficient.

Combining (1) and (2), x + k = 2 and 2x + k = 4
Solving we get, x = 2 and k = 0, which implies x > k; SUFFICIENT.

The correct answer is C.
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by amit2k9 » Wed Jul 20, 2011 3:12 am
yes i affirm that there must be a mistake with the question.

for the other opinion.

a x+k = 2 not sufficient.

b 2x+k = 4 not sufficient.

a+b

solving x= 2 and k=0. hence C it is.
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