First, use Partial Fractions to simplify .

If

.

Then

.

So and .

So .

Therefore .

So for your series:

.

Notice that if we expand this out...

Can you see that every term except for the first and last cancels?

So the sum is .

What do you think and equal?

P.S. A telescopic series is a series where everything except the first and last terms cancel.