*해설

<문제 해설>
출력=iR2
입력=i(병렬(R1,Ls)+R2) | 병렬(R1,Ls)=(R1*Ls)/(R1+Ls)
양변에 i로 나누면
(R2)/(((R1*Ls)/(R1+Ls))+R2)
양변에 R1+Ls 곱하면
(R2(R1+Ls))/(R1*Ls+R2(R1+Ls))
밑을 정리하면
(R2(R1+Ls))/(R1*Ls+R2*R1+R2*Ls))