1. For Each of the following systems determine whether the system is (1) causal, (2) linear, (3) shift-invariant (4) stable: (a) y(n)=x(n)u(n) (b) y(n)=x(n) (c) y(n)=nx(n+1) (d) y(n)=logx(n) (e) y(n)=x(n+2) 2. Compute the convolution y(n)=x(n)h(n) of the following signals: (a) x(n)={1,2,4}. (b) x(n)={1,2,1}.h(n)=x(n) (c) x(n)={1,2,3,4,5},h(n)=[1] (d) x(n)={1,2,3}h(n)={0,0,1,1,1,1,1} (e) x(n)={1,20,2,1}h(n)=x(n)