How Do You Simplify and Find the Interval of Convergence for a Power Series?

tolove
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Edit: Nevermind, figured it out. Thank you for readingOriginal problem:
Find the interval of convergence
\sumn=1 xn / n * √(n) * 3n

Ratio Test, right? an+1/a

I get to here and I can't figure out how to get rid of the ns:

lim n→∞ abs(x/3)* [n*√(n) / (n+1)*√(n+1)]

Solution,
They break apart evenly:
(n/(n+1)) * (n/(n+1)**(1/2)

(also, sorry this looks terrible. I'm not sure how to use the graphics options very well yet)
 
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tolove said:
Original problem:
Find the interval of convergence
\sumn=1 xn / n * √(n) * 3n

Ratio Test, right? an+1/a

I get to here and I can't figure out how to get rid of the ns:

lim n→∞ abs(x/3)* [n*√(n) / (n+1)*√(n+1)]

(also, sorry this looks terrible. I'm not sure how to use the graphics options very well yet)

Start with just the n/(n+1) part. Divide numerator and denominator by n and tell me what the limit of that is as n->infinity.
 
Dick said:
Start with just the n/(n+1) part. Divide numerator and denominator by n and tell me what the limit of that is as n->infinity.

Simplifies down to:
limn→∞ abs(x)/3 * (1/(1+1/n))**(3/2) = abs(x)/3

Thank you very much for your reply!
 
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