x^y = y^xx^(y/x) = y两边同时求导x^(y/x-1)*(y'x-y/x^2) = y'化简得y' = y*x^(y/x-3)/(x^(y/x)-1)若还要某点的导数值通过原式求出x y 带入上式即可
两边取对数,变为:ylnx=xlny 两边求导:y'lnx+y/x=lny+xy'/y 剩下就是求y'
不会啊```
