$$
i=C\frac{du}{dt}\\
\ \\
u=\frac{1}{C}\int_{-\infty}^{t}idt\\
\ \\
W=\int_{-\infty}^{t}Pdt=\int_{-\infty}^{t}Cu\frac{du}{dt}dt=\frac{1}{2}Cu^2(t)
$$
$$
电容\left\{\begin{array}{l}
串联：\frac{1}{C}=\frac{1}{C_1}+\frac{1}{C_2}+\cdots\\
并联：C=C_1+C_2+\cdots
\end{array}\right.
$$$$
u=L\frac{di}{dt}\\
\ \\
i=\frac{1}{L}\int_{-\infty}^{t}udt\\
\ \\
W=\int_{-\infty}^{t}Pdt=\int_{-\infty}^{t}Li\frac{di}{dt}dt=\frac{1}{2}Li^2(t)
$$
$$
电感\left\{\begin{array}{l}
串联：L=L_1+L_2+\cdots\\
并联：\frac{1}{L}=\frac{1}{L_1}+\frac{1}{L_2}+\cdots
\end{array}\right.
$$ 
