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by Stuart@KaplanGMAT » Mon Oct 26, 2009 1:31 pm
If by "solution" you mean "possible value for n", I'm not sure why n=0 doesn't work for all 5 answers, since anything to the power 0 = 1.

So, if you plug in n=0, all 5 equations solve to 1=1, which is true.
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by NikolayZ » Tue Oct 27, 2009 5:57 am
I came across this while doing some CAT. Actually i was confused too. But the right answer is A.

Explanation followed was something like that ( do not remember exactly):
When n is even, right and left side are opposite reciprocals, and when n is odd - reciprocals.
So the absolute value will be the same when n=0, but the sign will not be the same. And the sign will be the same for both sides when only n is odd.
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by sanjana » Tue Oct 27, 2009 7:24 am
I came across this question in One of the MGMAT cats.
I got it wrong obviously,and the explaination was really wordy!!
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by Ian Stewart » Tue Oct 27, 2009 8:22 am
n = 0 is only a solution for answer choices B and C; note that on the left side of A, and on the right side of D and E, the negative sign is not enclosed in brackets. If n = 0, then -2^n is equal to -1, and not to 1; by order of operations we evaluate the exponent before applying the negative sign. However, n=1 is a solution for D and E, which only leaves A as a possible answer.
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