the problem is almost solved, now, we have Then, if you consider does it telescope? what 'bout the other one?
What he means is that a telescoping sum is a sum that can be simplified by the cancelleling of terms through the addition that it implies.
e.g.
If you look carefully at this sum you can see that no matter how large n is that there will only be two terms left standing after what I call the addition wars. check it out
So after an uncountable number of n terms, who comes out of this war alive?
So now look at your problem with a trained eye. You have the ability to predict who's side you shoulb be on!