= (a) 2.21. Compute the convolution y[n] x[n] = a" u[n], α = β h[n] = ẞ"u[n], (b) x[n] == x[n] h[n] of the following pairs of signals: h[n] = a"u[n] (c) x[n] = (-)"u[n = 4] h[n] = 4"u[2 - n] (d) x[n] and h[n] are as in Figure P2.21.