函数y=2008x+cosx-sinx的2008阶导数等于( )

问题描述:

函数y=2008x+cosx-sinx的2008阶导数等于( )
A.2008
B.cosx-sinx
C.sinx-cosx
D.sinx+cosx

答案选B.
由归纳法易得
(sinx)^(n) = sin(x + n·π/2)
(cosx)^(n) = cos(x + n·π/2)
所以 (sinx)^(2008) = sinx ,(cosx)^(2008) = cosx