求数学帝请教一条导数题.求y' - 知识问答

求数学帝请教一条导数题.求y'

4个回答

两边取对数：
lny = x ln[cos(6x)]
两边对x求导：
y'/y = ln[cos(6x)] - 6xsin(6x)/cos(6x)
= ln[cos(6x)] - 6x tan(6x)
y' = y {ln[cos(6x)] - 6x tan(6x)}
= {ln[cos(6x)] - 6x tan(6x)} (cos 6x)^x

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