In a digital communications system, the power levels of discrete signals are modeled by the function P(k)=k2−10P(k) = k^2 - 10P(k)=k2−10, where kkk is an integer representing the signal index. Use the method of proof by contradiction to prove that it is impossible for any signal power P(k)P(k)P(k) to be exactly divisible by 4.