4. Discussions 1) What is the advantages of the impulse and step response? 2) Find the impulse response of the following system: Y[n] = x[n] + x[n - 1] - 0.8y[n - 1] compute the length of the resultant sequence. 3) Find the step response of the following system: Y[n] = x[n] + x[n 1] - 0.8y[n - 1] compute the length of the resultant sequence. 4) Find the impulse response of the following system: Y[n] = x[n] -0.8x[n - 1] + 1.2x[n - 2] compute the length of the resultant sequence