设f(x,y)=esin(z+2y),求fx(0,π/4);fy(0,π/4).
fx(x,y)=-e-x sin(x+2y)+e-xcos(x+2y), fy(x,y)=2e-xcos(x+2y), fx(0,π/4)=-sin(π/2)+cos(π/2)=-1, fy(0,π/4)=2•1•cos(π/2)=0.
设f(x,y)=esin(z+2y),求fx(0,π/4);fy(0,π/4).
fx(x,y)=-e-x sin(x+2y)+e-xcos(x+2y), fy(x,y)=2e-xcos(x+2y), fx(0,π/4)=-sin(π/2)+cos(π/2)=-1, fy(0,π/4)=2•1•cos(π/2)=0.