. prove the following energy and power properties: Er(t) total energy of the signal z(t) Piz(t)]:= average power of the signal, r(t) if r(t) is periodic. (a) Ex(t+b)] = Er(t)] and Pr(t+b)] = Px(t)] (time shift do not affect power or energy) (b) Elar(1)] = a Er(t)] and Par(t)] = a*Pr(t)] (scaling by a scales energy and power by la12) (c) Er(at)Er()] and Pr(at)] Pr(t) if a>0 (time scaling changes energy by but doesn't affect power)