五 八.z=∫(x,L,), u=g(x, v,y), v=h(x, y), xyyx azof,ofog,amh,可fhv 十 十 十 axax au ax av ax av ax =f+f281+f1g2h+f3h1, az_oo,h,g、ofmh du dv =f282h2+f283+∫3h2 K心五. 八. ( , , ), ( , ), ( , , ), u g x v y v h x y z f x u v = = = z xuv xvyxy xy xh vf xh vg xg uf xf xz   +   +   +  =  ( ) , 1 2 1 1 2 1 3h1 = f + f g + f g h + f yh vf yg yh vg uf yz   +  +    =  ( ) . 2 2 2 2 3 3h2 = f g h + f g + f