对于微分方程<img src="/lqwvjeImg/ff/ff21602a533a16e0675fd6ffea96d250.png"style="width:200px;height:40px;">,利用待定系数法求其特解<img src="/lqwvjeImg/ec/ec19d768e226b5c136d4669898417c8a.png"style="width:30px;height:40px;">时,下列特解设法正确的是 ( )<br>·<img src="/lqwvjeImg/1c/1ca351bbba09ff9be5acbdb72b19ad2b.png"style="width:110px;height:40px;"><br>·<img src="/lqwvjeImg/db/db4563e0f97655b5942b7538fee3d95e.png"style="width:182px;height:40px;"><br>·<img src="/lqwvjeImg/83/836bf1aac1de32b5052b04db246c5d23.png"style="width:121px;height:40px;"><br>·<img src="/lqwvjeImg/2b/2b169c6bce6a1d67ab8dcf3e7001874b.png"style="width:132px;height:40px;">