Energy
$ E = \int_{T2}^{T1} |x(t)|^2\ dt \! $
$ E = \int_{1}^{2} |3x|^2\ dt \! $
$ E = [x^3]_{t=1}^{t=2} $
Power
$ P =\frac{1}{t2-t1} \int_{t1}^{t2} |f(t)|^2\ dt \! $
$ P =\frac{1}{2-1} \int_{1}^{2} |3x|^2\ dt \! $
$ P = [x]_{t=1}^{t=2} = 1 $
