Answer:
(a)
(b)
if r<1, then it converges absolutely
if r>1, then it diverges
if r=1, then the test is inconclusive
Step-by-step explanation:
The ratio test is:
if L<1, then it converges absolutely
if L>1, then it diverges
if L=1, then the test is inconclusive
I'm assuming that they used r instead of L. Anyway, to do the ratio test, you plug in n+1 into the equation and make that numerator.
Then you plug in n into the same equation and make that your denominator.
In our case, our equation is .
So lets plug in n+1 and make that our numerator.
Now lets plug in n and make that our denominator.
Now set up the ratio test.
if you simplify this, you would get (view image for the steps)
L = infinity, which is > 1, therefore this series diverges