Using the integral test, how do you show whether (1/sqrt (n+1))(1n+1) diverges or converges?

1 Answer
Jun 11, 2015

I would assume that this goes from n = 1n=1 to oo? The domain must be [k,oo][k,] in order for this to work. If so, I've already answered this here:
http://socratic.org/questions/using-the-integral-test-how-do-you-show-whether-sum-1-sqrt-n-1-diverges-or-conve#151880

Overall, it diverges, because the integral evaluates as oo. The gist of it is, integrate it replacing nn with xx, and show that it will result in oo when evaluated from 11 to oo.

You should also know that this is a "p-series":

sum_(n = 1)^(oo) 1/((npmk)^p)n=11(n±k)p
where k in RR (k is in the set of real numbers)

If p > 1, the sum will converge, whereas if p <=1, the sum will diverge. When p = 1, it's called the harmonic series