C I(t)=\int_{\tau=0}^{\tau=t} f_{1}(\tau) f_{2}(t-\tau) d \tau=\int_{\tau=0}^{\tau=t} f_{1}(t-\tau) f_{2}(\tau) d \tau\label{eqn:6.1} \[C I(t)=\int_{\tau=0}^{\tau=t} f_{1}(\tau) f_{2}(t-\tau) d \...C I(t)=\int_{\tau=0}^{\tau=t} f_{1}(\tau) f_{2}(t-\tau) d \tau=\int_{\tau=0}^{\tau=t} f_{1}(t-\tau) f_{2}(\tau) d \tau\label{eqn:6.1} C I(t)=\int_{\tau=0}^{\tau=t} f_{1}(\tau) f_{2}(t-\tau) d \tau=\int_{\tau=0}^{\tau=\infty} f_{1}(\tau) f_{2}(t-\tau) d \tau \nonumber L[C I(t)]=L\left[\int_{\tau=0}^{\tau=\infty} f_{1}(\tau) f_{2}(t-\tau) d \tau\right]=\int_{t=0}^{t=\infty} e^{-s t}\left[\int_{\tau=0}^{\tau=\infty} f_{1}(\tau) f_{2}(t-\tau) d \tau\right] d t \nonumber