Hey I'm stuck on this Q and I would be grateful for any replies.

I have tried twice to write the problem in latex but unfortunately I am not proficient enough in it.

I have attached the Q NB it is Q2 on the attached photo

Also I have attached the graph that I think is right for the first part

but my real Q is for part 1 how do you show that that integral is equal to that sum? I can see it clearly from

the graph but I don't know how to show it?

I'll work on part two later.

I would be really grateful for any replies.

Thanks from James