4.设 =(x)^3(y)^2+3, 则 dfrac ({partial )^2z}(partial ypartial x)= () .-|||-(A)6x^2y; (B)6xy^2; (C)6x^2y^2; (D) 6xy .-|||-5.设L为圆周 ^2+(y)^2=1, 则 int ((x)^2+(y)^2)dy= () .

sin (x+2y-3z)=x+2y-3z, 则 dfrac (partial z)(partial x)+dfrac (partial z)(partial

1.已知 sin (3x-2y+z)=3x-2y+z, 则 dfrac ({partial )^2z}(partial xpartial y)= __

dfrac ({sigma )^2z}(partial {y)^2} 和 dfrac ({partial )^2z}(partial xpartial y):-

33.设函数 z=z(x,y) 由方程 +x=(e)^z-y 所确定,则 dfrac ({partial )^2z}(partial ypartial x)=

2.设 (xy,x+y)=(x)^2+(y)^2+xy (其中, =xy =x+y), 则 dfrac (partial f)(partial u)+dfrac

5.设 sin (x+2y-3z)=x+2y-3z, 证明: dfrac (partial z)(partial x)+dfrac (partial z)(pa

若z=f(x,y),x=u+v,y=u-v,则(partial^2z)/(partial upartial v)=(partial^2z)/(partial x

殳 =(u)^2ln v =dfrac (y)(x), =2x-3y,-|||-则 dfrac (partial z)(partial y)= ()-|||-A

设 =f(xy,(x)^2+(y)^2), 其中 f 可微,则 dfrac (partial z)(partial x)= __

求下列函数的 dfrac ({a)^2z}(a{x)^2} ,dfrac ({partial )^2z}(partial xpartial y) ,dfrac