Chapter 2 Problems solution 2.7 A linear system S has the relationship =∑ xkgn-2 between its input xn] and output[n] gn]=un]-un-4 (a)x[小]=o[n-1]y[小=[n-21-u[n-6 (b)x{]=o8[n-2]y[小=utn-4]-m-8 (c)s is time-varying. uIn+uln =2u 6n-6n2 Chapter 2 Problems Solution 2.7 A linear system S has the relationship yn xkgn k k =  − 2 + =− between its input and output xn yn gn= un−un−4 (a 1 ) x n n   = −    y n u n u n   = − − −  2 6    (b 2 ) x n n   = −    y n u n u n   = − − −  4 8    (c) S is time-varying. (d ) x n u n   =   y n u n u n   = + −    2 = − − − 2 1 u n n n        