Sequence increase/decrease I need help determining if the following sequences are increasing, decreasing or not monotnic. Any help would be great.
I think that for c) it is not monotonic as well as for a. 
a) $\frac{\cos(n)}{5^n}$
b) $\frac{1}{5n+8}$
c) $\frac{n-5}{n+5}$
d) $\frac{\sqrt{n+5}}{8n+5}$
Thank you! :)

a) is not monotnic
b) is decreasing
c) $\frac{n-5}{n+5}=1-\frac{10}{n+5}$ is increasing
d) is decreasing.
