求导高数题目一枚,设方程x=y∧y 确定y是x的函数,求dy.

问题描述:

求导高数题目一枚,设方程x=y∧y 确定y是x的函数,求dy.

ylny = lnx
两边对x求导:
y'lny + y(1/y)y' = 1/x
y'lny + y' = 1/x
(lny + 1)y' = 1/x
y' = 1/[x(lny + 1)]