Yep. It's a telescoping series.
nope, that's not right. you are missing some guys. for instance, 1/2 doesn't cancel. check again
you need to evaluate the first n terms
try the following just to see a pattern:
1st term + 2nd term + 3rd term + 4th term + 5th term + ...... + (n - 3)th term + (n - 2)th term + (n - 1)th term + nth term
where you see the dots, you skip those, just jump from the 5th term to the (n - 3)th term. our goal is to see the pattern of what cancels and what stays. if you are keen on picking up the pattern early, you might not have to test that many