求导：y = ( tan x )＾3 [为什么等于3 ( sec x )＾4 - 3 ( sec x )＾2 ]
人气：154 ℃ 时间：2020-02-02 17:44:44
解答
y=( tan x )＾3 y'=3( tan x )＾2*(tanx)' =3( tan x )＾2*sec^2x =3sin^2x*sec^2x*sec^2x =3seC^4x*sin^2x =3seC^4x*(1-cos^2x) =3sec^4 x -3sec^4xcos^2x =3sec^4 x -3sec^2 x
