My problem is that I can't seem to substitute numbers into an integral properly !

One of my concerns is that my evaluation of I0 is different if I use the integral or use the expression (-sinh1 and sinh1 respectively). Since the expression is correct, as it was a "prove that" question and therefore written in the book, i'm not really sure why i'm getting two different answers.

I can't see any problem with my working for part (b). That's just one of the reasons why this is so infuriating!

Anyway, if anyone could see what i'm doing wrong it would be a great help.