求2阶导数,
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求2阶导数,
![](http://img.wesiedu.com/upload/1/c5/1c51024695fb09847b510d296d3e6764.jpg)
![](http://img.wesiedu.com/upload/1/c5/1c51024695fb09847b510d296d3e6764.jpg)
![求2阶导数,](/uploads/image/z/4993934-14-4.jpg?t=%E6%B1%822%E9%98%B6%E5%AF%BC%E6%95%B0%2C%26nbsp%3B)
y=tan(x+y)
y'=sec^2(x+y)*(1+y')
y'=-sec^2(x+y)/tan^2(x+y)=-1/sin^2(x+y)=-csc^2(x+y)
y''=-2csc(x+y)*[-csc(x+y)*ctg(x+y)]*(1+y')
=2csc^2(x+y)ctg(x+y)(1+y')
=2csc^2(x+y)ctg(x+y)(1-csc^2(x+y))
=-2cos^2(x+y)/sin^5(x+y)
=-2ctg^2(x+y)*csc^3(x+y).
再问: 明天看看,对了就给采纳,晚安。
再答: ok
再问: 没找到这条,太抱歉刚才采纳
y'=sec^2(x+y)*(1+y')
y'=-sec^2(x+y)/tan^2(x+y)=-1/sin^2(x+y)=-csc^2(x+y)
y''=-2csc(x+y)*[-csc(x+y)*ctg(x+y)]*(1+y')
=2csc^2(x+y)ctg(x+y)(1+y')
=2csc^2(x+y)ctg(x+y)(1-csc^2(x+y))
=-2cos^2(x+y)/sin^5(x+y)
=-2ctg^2(x+y)*csc^3(x+y).
再问: 明天看看,对了就给采纳,晚安。
再答: ok
再问: 没找到这条,太抱歉刚才采纳