Proving Series Divergence: Convergence of a_n w/o Explicit Formula

[CrusaderSean]

Given a_{n} > 0 and \sum a_{n} diverges, show that \sum \frac{a_{n}}{1+a_{n}} diverges.
Since I don't have an explicit form for the series, I can't apply any of the standard tests. I'm not sure where to start on this problem. I know the criteria for convergence/divergence, namely tail end of series has to converge or cauchy criterion condition. But I don't see how that helps without knowing what series looks like. Please steer me in the right direction.

 

[Fermat]

If a series diverges, what happens to to its reciprocal ?

 

[CrusaderSean]

I would say reciprocal converges, but apparently it's not enough to bring original series to convergence... I thought about this a little more and I think I'll analyze it based on how a_{n} diverges. that is, does it go to zero, constant, or infinity as n goes to infinity and try to bound the reciprocal from below to show series diverges.

 

[amcavoy]

For a_n>1:

\frac{a_n}{1+a_n}>\frac{1}{2}

For a_n\leq 1:

\frac{a_n}{1+a_n}\geq\frac{a_n}{2}