In Problems 36 through 38, apply the convolution theorem to derive the indicated solution x(t) of the given differential equation with initial conditions x (0) = xn (0) = 0. 36. x" + 4x = f(t); x(t) = 1/2 integral^t_0 f(t - tau) sin 2 tau d tau 37.x" + 2x' + x = f(t); x(t) = integral^t_0 tau e^-tau f(t - tau) d tau