1. The problem statement, all variables and given/known data Let an be a series of positive elements such as lim_n->infinity_an=0 and the series Sigma_n=1-infinity_an diverge. Let bn=(-1)^n*an Prove or find counterexamples for the next propositions: 1. 1. Sigma_bn diverge. 2. Sigma_bn doesn't absolutely converge. 3. Sigma_bn converge. 2. Relevant equations 3. The attempt at a solution I need a counterexample for 3...I have a counterexample for 1 and I think I can prove 2... 3 is all I need TNX everyone!