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Re: Is q^b a divisor of p^a ? 1. a>b 2. p is a multiple of q [#permalink]
E.

a = -1 > b = -2
p=6 a multiple of q = 2.

Also, q = p can be zero.
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Re: Is q^b a divisor of p^a ? 1. a>b 2. p is a multiple of q [#permalink]
I would expect a real GMAT question to define q, p, a, and b positive integers. If this is the case, then C should be the correct answer.

From 2, p=mq
p^a/q^b=m^aq^a/q^b=m^aq^(a-b)
From 1, a-b>0
then p^a/q^b=m^aq^(a-b) is also an integer. In other words q^b is a divisor of p^a.

However if pqab are not defined, then we don't know if they are integers. For example, a-b might be 1/2 or something. Then the answer would be E.
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Re: Is q^b a divisor of p^a ? 1. a>b 2. p is a multiple of q [#permalink]
OA is C

HongHu, I noted in the Question that all numbers are integers.
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Re: Is q^b a divisor of p^a ? 1. a>b 2. p is a multiple of q [#permalink]
You are very right AJB, though I would prefer they are positive integers, them being integers are the most important one and it is defined in the question. Now can 0 be a divisor to another number? :hmmm:
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Re: Is q^b a divisor of p^a ? 1. a>b 2. p is a multiple of q [#permalink]
If p,q,a,b are not positive integers, How can the answer be C?.

p=6, q=2, a=-1, b=-2 satisfy both statements and yield a 'no' answer. One can find several easy examples of 'yes' answer for a given set of p,q,a,b if all are positive and both statements are true.
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Re: Is q^b a divisor of p^a ? 1. a>b 2. p is a multiple of q [#permalink]
I believe that the domain is the natural numbers when we are talking about multiples and factors. However, 0 should be included. 0 is a multiple of any number, including 0 itself. In other words for this question both q and p can be zero to satisfy (2), and then we would get a "No" to the question (since 0 can't be a divisor) instead of "Yes" when they are not zeros.

Also to make sure q^b and p^a are natural numbers so that "divisor" is defined, a and b must not be negative.

Therefore for this question to be strictly defined it should say all numbers are positive integers.



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