Chapter 10, Problem 10.11P

Two voltage waves of equal amplitude V_0, which have different frequencies $\omega$ and $3\omega$ (with corresponding phase constants $\beta$ and $\text{3}\beta$ ), propagate in the forward z direction in a lossless transmission line. Find an expression for the net voltage wave formed by the superposition of the given voltages. To do this, express both waves in complex instantaneous form (retaining the time-dependent terms). Combine the two algebraically, and convert the result to real instantaneous form to yield a single-term wave function. Plot your result as a function of $\beta z$ at t = 0.