Answer
(a) divergent
(b) absolutely convergent
(c) could converge or diverge
Work Step by Step
a) By the definition of the ratio test, $r\gt1 $ and thus the series must diverge.
b) Since r is less than 1, the series is absolutely convergent by the ratio test.
c) The ratio test fails when $r=1$. So the series could converge or diverge.
