Prove that the amplitude I0 of the steady periodic solution of Eq. (6) is maximal at frequency ! D 1=pLC.

L35 - 2 Substitution Rule If u = g(x)siaiblinwergein interval I and f is continuous on Ihn ▯ ▯ f(g(x))g (x) dx = f(u)du ▯ ex. (3x +1 ( x + x − 2) dx =