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问题 单项选择题

若A、B为非零常数，C1、C2为任意常数，则微分方程y"+k2y=cosx的通解应具有形式（）。

A．C1coskx+C2sinkx+Asinx+Bcosx

B．C1coskx+C2sinkx+Axcosx

C．C1coskx+Czsinkx+Axsinx

D．C1coskx+C2sinkx+Axsinx+Bxcosx

答案

参考答案：C

解析：

齐次方程的通解为C1coskx+C2sinkx，只需验证哪一个是非齐次方程的特解，如果非齐次方程的特解形式为Asinx+Bcosx，说明此时k≠1，经验证可知特解为

cos，

阅读理解与欣赏

修改下列病句。（4分）                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             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选择题

酸、碱、盐之间发生复分解反应的实质是离子之间的互换反应，两种离子若能结合成沉淀、气体或水，反应便能发生．由此判断，下列物质中一般不和其它物质发生复分解反应的是（　　）

A．NaOH

B．KCl

C．NaNO3

D．CuSO4
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