作业帮求2阶导数,
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求2阶导数,
求2阶导数,
求2阶导数,
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).