`{:(Ri+L(di)/(dt)=V),(4i+2(di)/(dt)=10\ sin\ 5t),(4I+2(sI-i(0))=10 5/(s^2+25)):}`
Assume `i_0=i(0)=0`.
`4I+2sI=50/(s^2+25)`
`(2+s)I=25/(s^2+25)`
So `I=25/((s+2)(s^2+25))=A/(s+2)+(Bs+C)/(s^2+25)`
`25 = A(s^2+ 25) + (Bs + C)(s + 2)`
We need to solve for A, B and C.
First, let `s = −2` and this gives
`25 = 29A`
Thus `A = 25/29`
Next, we equate coefficients of `s^2`:
`0=A+B` gives `B=-25/29`
Equating coefficients of `s`:
`0=2B+C` gives `C=50/29`
So
`{: (I,=25/((s+2)(s^2+25))),(,=25/(29(s+2))-25/29 s/(s^2+25)+50/29 1/(s^2+25)),(,=25/29(1/(s+2)-s/(s^2+25)+2/5 5/(s^2+25))):}`
So we have
`i=25/29(e^(-2t)-cos\ 5t+2/5sin\ 5t)\ "A"`
Here is the graph of `i(t)`:
