填空题
1
设z=xyf,f(u)可导,则xz′x+yz′y=().
设f(u)可微,且f′(0)=,则z=f(4x2-y2)在点(1,2)处的全微分dz=().
设z=xex+y+(x+1)ln(1+y),则dz=().