1. The problem statement, all variables and given/known data Is the following system linear: [tex] y(n) = x(n) + 0.8y(n-1) [/tex] 3. The attempt at a solution I'm really stuck on this one. My idea was to assume that the system is casual, find the impulse response and then use the fact that: [tex] y(n)=x(n)*h(n) [/tex]. However, if I assume that the output is the convolution of the impulse response and the input, I have ALREADY ASSUMED (and not proven) that the system is linear. So I am lost. I can't wrap my brain around the fact that the output depends on the input and the previous output. Another idea I had is that if I show that I input a sinusoid and I get a scaled and phase shifted sinusoid, then the system is LTI. Any help?