# Problem with Hard Discrete Convolution

#### J_Y

Joined May 5, 2009
1
Hi guys
I've been racking my brains over this question for over 3 days..

The question has several parts, which I think I did correctly for the most part...
I am given 2 equations

From there I z-transformed the x[n] and calculated H[z] and h[n]

It also asked for y[n], which I calculated to be

Then the last part is where my problem lies
It requires me to prove y[n] through convolution of x[n] and h[n], with the assumption that the system is causal

Question 1: Can you even convolve a non causal input with a causal system?
Question 2: This is my attempt http://www.scribd.com/doc/14972175/Proving-via-Convolution. I got the answer of

Where am I going wrong???