∵z=x²-xy+y²-2x+y∴αz/αx=2x-y-2,αz/αy=-x+2y+1,α²z/αx²=2,α²z/αy²=2,α²z/αxαy=-1∵令αz/αx=2x-y-2=0,αz/αy=-x+2y+1=0得x=1,y=0∴当x=1和y=0时,(α²z/αx...