First find the Fourier series of given pulse that is And f_m from (2) ⇒ 4 kHz When we multiply x₁(t) and x₂(t - t) We get term like f_s ± f^m, 2f_s ± f_m, 3f_s ± f^m, 4f_s ± f_m and f_s = 10 kHz f_m = 4kHz Hence from above relation (10+4) kHz ⇒ 14 kHz signal will be present in x(t).