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factor problem

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factor problem

by jamesk486 » Wed Apr 11, 2007 1:16 am
X is a prime and y is a positive integer, How many different factors of (2^3)*(x^y) are there?
(1) x=5
(2) y=3

I got stuck in the middle, after figuring out that the number of factors would be (3+1)(y+1)...but someone told me that x could not be 2 or something like that..anyways i'm pretty lost!
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Re: factor problem

by ajith » Thu Apr 12, 2007 1:51 am
jamesk486 wrote:X is a prime and y is a positive integer, How many different factors of (2^3)*(x^y) are there?
(1) x=5
(2) y=3

I got stuck in the middle, after figuring out that the number of factors would be (3+1)(y+1)...but someone told me that x could not be 2 or something like that..anyways i'm pretty lost!
If 2 is a factor of x the number of factors of (2^3)*(x^y) would not be (3+1)(y+1)

So we need to know x as well as y to determine the number of factors.

:)
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by jamesk486 » Thu Apr 12, 2007 6:45 am
I'm still confused...because I thought the answer would be B but its C...
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by RAGS » Thu Apr 12, 2007 7:12 am
Well here as u know the no of factors can be found out by getting the no of prime factors as u said (1+3)(y+1)

statement 1 gives x=5 whickh is not sufficient since u need to know Y

statement 2 gives y=3
here consider the case where x=2 then we have no of factors will be
for 2exp(6) will be (6+1) ie 7
but for x as any prime other than 2 the ans would be (3+1)(3+1) ie 16

but both together solves the problem by giving a value to X
So C
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by Cybermusings » Thu Apr 12, 2007 7:25 am
Thanks RAGS...your explanation has lifted the cloud
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