Chapter 8.3, Problem 4E

Suppose ${\displaystyle \sum a_n}$ and ${\displaystyle \sum b_n}$ are series with positive terms and ${\displaystyle \sum b_n}$ is known to be divergent.

(a) If a_n> b_n for all n. what can you say about ${\displaystyle \sum a_n}$? Why?

(b) If a_n. < b_n. for all n, what can you say about ${\displaystyle \sum b_n}$? Why?