1. Let the discrete-time signal be defined by z[n] be defined by (additional values are zero) 0 000 -6 -2 -2 -2 2 -1-2-1 -1 2 2 2 4 00000 6 n a. Express z[n] as a sum of step functions. b. Is z[n] an energy signal, a power signal or neither? If z[n] is an energy signal, compute its energy. If z[n] is a power signal, compute its power. If z[n] is neither, explain why. c. Is z[-n +7] causal? 2. Let the discrete-time signal z[n] be shown below. z[n] 0000000 -2 -1 000000 n a. Express z[n] as a sum of step functions u[n]. b. Sketch y[n] = m=1(m + 1)z[n 3m]. Remember to label your axes. - c. Is z [n] an energy signal, a power signal or neither? If z [n] is an energy signal, compute its energy. If z[n] is a power signal, compute its power. If z[n] is neither, explain why.