1. The problem statement, all variables and given/known data Hello, everyone This is a practice problem from BP Lathi's Signal Processing and Linear Systems book, exercise E3.2 for those that have the book. http://img818.imageshack.us/img818/2838/imag0736i.jpg [Broken] Here is the exercise E3.2 http://img269.imageshack.us/img269/7095/imag0734o.jpg [Broken] 2. Relevant equations http://img710.imageshack.us/img710/8167/imag0737copy.jpg [Broken] The formula for "c" http://img4.imageshack.us/img4/827/imag0738copy.jpg [Broken] 3. The attempt at a solution Here is my trial http://img836.imageshack.us/img836/552/imag0735m.jpg [Broken] I can't get the given answer. As far as I know, I there are no math errors in my computation. I am sure its simple stuff. But I really like to know what am I doing wrong here. Thanks in advance.