设Z=f(x,y)且f(x,x^2)=x^3+1,fx(x,x^2)=x^2-2x^3,则求fy(x,x^2)=?
问题描述:
设Z=f(x,y)且f(x,x^2)=x^3+1,fx(x,x^2)=x^2-2x^3,则求fy(x,x^2)=?
答
f(x,x^2)=x^3+1,
Zx=3x^2
Zx=fx+2x *fy=x^2-2x^3+2xfy
fy=(Zx-x^2+2x^3)/2x
=(3x^2-x^2+2x^3)/2x=x/2+x^2