\[ E_x = \sum_{n=-\infty}^{+\infty} \left| x\left
\[ n \\right\]\right|^2 \] \[ P_x = \lim_{N\to\infty} \frac{1}{2N + 1} \sum_{n = -N}^{N} \left| x
\[n\]\right|^2\]
\[ E_x = \sum_{n=-\infty}^{+\infty} \left| x\left
\[ n \\right\]\right|^2 \] \[ P_x = \lim_{N\to\infty} \frac{1}{2N + 1} \sum_{n = -N}^{N} \left| x
\[n\]\right|^2\]