Fx有二阶连续导数可以求到二阶吗答:Fx有二阶连续导数可以求到二阶。无区别 y=f(2x), y‘=2f’(2x), y‘‘=4f’(2x),y=f(x^1/2), y’=f'(√x)/(2√x) y’=(1/4)[2xf''(x^1/2)-f'(√x)]/(x^(3/2))。(x)于[a,b]二阶可导,说明f(x)在(a,b)光滑,且连续于[a,b]这里顺便说一下光滑的意思,...
为什么二阶偏导数连续 ,混合偏导就相等啊??答:F(x,y)=x^3y^3sin(1/(xy)),xy≠0. F(x,y)=0,xy=0. 1.xy=0,显然有 Fx'(x,y)=Fy'(x,y)=0. 2.xy≠0, Fx'(x,y)=3x^2y^3sin(1/(xy))-xy^2cos(1/(xy)), Fy'(x,y)=3x^3y^2sin(1/(xy))-x^2ycos(1/(xy)). 3. xy=0,显然有 Fxy''(x,y)=Fyx''(...