求题2-18图所示电路的输入电阻。

A . 零 B . R C . 无穷大

<img src='https://img2.soutiyun.com/ask/2020-10-07/9709100477967.png' />

<img src='https://img2.soutiyun.com/ask/2021-01-05/978704111515359.png' /><img src='https://img2.soutiyun.com/ask/2021-01-05/978704176869097.png' />

试求题4-25图所示电路中电容电压u_c(t)在t＞0时的函数式.已知u_c(0_)=80V. <img src='https://img2.soutiyun.com/ask/2020-10-09/971120741399575.png' />

<img src='https://img2.soutiyun.com/ask/uploadfile/5364001-5367000/2968ad2b913847aaeafa85b7fd6637c5.jpg' />

求题3-5-2图所示电路以uc(t)为输出变量的输入-输出方程. <img src='https://img2.soutiyun.com/ask/2020-10-09/971112277960494.jpg' />

试求题4-27图所示电路在开关闭合后的零状态响应i(t)(图中Us为一直流电压). <img src='https://img2.soutiyun.com/ask/2020-10-09/971121216666759.png' />

<img src='https://img2.soutiyun.com/ask/2020-10-10/971174571953912.jpg' />

试求题9-12图所示电路的零状态响应i₁(t)和i₂(t). <img src='https://img2.soutiyun.com/ask/2020-10-10/971200443931704.jpg' />

求题9-17图所示电路的零状态响应i(t).要求对此电路的复频域模型用戴维宁定理求出i(t)的象函数I(s),进而求出i(t). <img src='https://img2.soutiyun.com/ask/2020-10-10/971200769947351.jpg' />

求题4-5-1图所示电路的冲激响应i(t). <img src='https://img2.soutiyun.com/ask/2020-10-09/971118180112078.jpg' />

求题4-3-1图所示电路的冲徼响应u_c(t)和i(t),并用阶跃响应的导数对所求结果予以校验. <img src='https://img2.soutiyun.com/ask/2020-10-09/971117740183915.png' />

求题2.25图所示电路中A、B端口的等效电阻。已知R₁=2Ω;R₂=12Ω,R₃=5Ω,R₄=8Ω,R₅=10Ω,R₆=14Ω。 <img src='https://img2.soutiyun.com/ask/2020-10-07/970904454837801.png' />

<img src='https://img2.soutiyun.com/ask/2020-10-09/971091491072552.png' />

<img src='https://img2.soutiyun.com/ask/2020-10-11/971295964907616.jpg' />

<img src='https://img2.soutiyun.com/ask/2020-12-25/97778751420716.png' />

<img src='https://img2.soutiyun.com/ask/2020-10-07/970904369406914.png' />

<img src='https://img2.soutiyun.com/ask/2020-12-28/978030790456659.png' />

<img src='https://img2.soutiyun.com/ask/2020-12-29/978113649236104.png' />

<img src='https://img2.soutiyun.com/ask/2020-09-16/969105779209809.png' />

<img src='https://img2.soutiyun.com/ask/2020-10-09/971104695662811.jpg' />

<img src='https://img2.soutiyun.com/ask/2020-09-16/96910631387039.png' />