Use Ratio Test to find the convergence of the following series?

#sum_(n=0)^oo (n!)/999^n#

1 Answer
Mar 31, 2018

#sum_(n=0)^oo(n!)/(999^n)-># Does not converge

Explanation:

The ratio test tells us that if we have a series

#sum_(n=0)^ooa_n#

then if #lim_(n->oo)abs(a_(n+1)/a_n)<1#, the series converges.

Let's test #sum_(n=0)^oo(n!)/(999^n)#

#rArra_(n+1)/a_n=(((n+1)!)/(999^(n+1)))/((n!)/(999^n))=((n+1)!)/(999^(n+1))*(999^n)/(n!)=(n+1)/999#

#lim_(n->oo)abs((n+1)/999)=+oo#

Because this limit diverges, the ratio test tells us that the series does not converge.