隐函数求导:y+iny=x确定隐函数y=y(x),求y'和y''.

问题描述:

隐函数求导:y+iny=x确定隐函数y=y(x),求y'和y''.

y+lny=x,两边对x求导数:y'+(1/y)*y'=1,所以:y'=y/(y+1)
对y'两边求对x的导数:y''=(y'*(y+1)-y*y')/(y+1)^2=y'/(y+1)^2=y/(y+1)^3