Limit Test on Series: Summation from n=0 to Infinity of n!/1000^n

cue928
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Series: summation from n=0 to infinity of n!/1000^n

I can look at that and see the limit is not going to zero but how do you show that? Also, were it not in the first section of the book (i.e. before the ratio test), I would have tried to use the ratio test on it - is that acceptable to do? I got infinity for the answer under the ratio test, btw.
 
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cue928 said:
Also, were it not in the first section of the book (i.e. before the ratio test), I would have tried to use the ratio test on it - is that acceptable to do?
Sure, why not?

I can look at that and see the limit is not going to zero but how do you show that?
Do you think n!>1000^{n} for some large n to be true? If so, could you manipulate the rational function using this knowledge?
 
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There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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