Convolution of two sets In my systems and signals course I had been asked a question about finding the convolution of two sets.
I was given:
\begin{align}
x[n] &amp;= \{3,2,1\}\\  
h[n] &amp;= \{1,-2,3\}\\  
\text{Find}\quad y[n] &amp; = x[n]\star h[n]
\end{align}
I have no idea on how to find the convolution of two sets. Any help is appreciated.
If it is difficult for you to remember or calculate the convolution of two sequences then you may try doing it as polynomial multiplication. 
Think of x[n] and h[n] as polynomial coefficients. So we have 
Px = 3x^2 + 2*x + 1
Ph = 1x^2 - 2*x + 3

Remember that linear convolution of two sequences is polynomial multiplication. Therefore 
Py = Px * Ph
Py = (3x^2 + 2*x + 1) * (1x^2 - 2*x + 3)
Py = 3x^4 + 2x^3 - 6x^3 + x^2 + 9x^2 - 4x^2 + 6x - 2x + 3
Py = 3x^4 - 4x^3 +6x^2 + 4x + 3

Now writing the polynomial coefficients back in sequence format 
y[n] = {3, -4, 6, 4, 3}