please help to solve the real and imaginary part of this question ,thanks

The function u(x, t) = er(x+ct) is another solution to the wave equation at2 Let's investiage the case when c = 5 + 3i . Then . The real part of u is . The imaginary part of u is So the function oscillates in the complex plane, but these oscillations are dampened by the exponential term. As time goes on lim u(x, t) = 0 t-+00