Problem:

Convince me \(\displaystyle an=\frac{1}{n^2+n}\) converge to zero.

I tried it with an=1

\(\displaystyle \frac{1}{1^2+1}=\frac{1}{2}\)

\(\displaystyle \frac{1}{(1/2)^2+(1/2)}=\frac{4}{3}\)

\(\displaystyle \frac{1}{(4/3)^2+(4/3)}=\frac{9}{28}\)

It doesnt go down to zero....