Question

设z=f(x,y),且f(x,x^2)=x^3+1,f'x(x,x^2)=x^2-2x^3,则f'y(x,x^2)=(

Answer 1

选D.

dz=3(x^2)dx

dy=2xdx

dz=f'xdx+f'ydy

3(x^2)dx=(x^2-2x^3+2x*f'y)dx

f'y=x+x^2