[试题]化简下列各式:(1)3(xy-2z)+(-xy+3z);(2)-4(pq+pr)+(4pq+pr) ;(3)(2x-3y)-(5x-y) ;(4)-5(x-2y+1)-(1-3x+4y);(5)(2a²b-5ab)- 2(-ab-a²b) ;(6)1-3(x-½y²)+(-x+½y²)。
3设 +2y+z-2sqrt (xyz)=0, 求 dfrac (partial z)(partial x) 及 dfrac (partial z)(parti
3.设 +2y+z-2sqrt (xyz)=0 ,求 dfrac (partial z)(partial x) 及 dfrac (partial z)(part
3.设 +2y+z-2sqrt (xyz)=0, 求 dfrac (partial z)(partial x) 及 dfrac (partial z)(part
例1 求函数 =(e)^x+2y 的所有二阶偏导数和 dfrac ({a)^3z}(partial ypartial {x)^2}
求椭球面dfrac ({x)^2}(2)+dfrac ({y)^2}(3)+dfrac ({z)^2}(4)=1上点dfrac ({x)^2}(2)+dfrac
微分方程dfrac (dy)(dx)=dfrac ({y)^2+(x)^3}(2xy)的通解为:dfrac (dy)(dx)=dfrac ({y)^2+(x)^
5.设 sin (x+2y-3z)=x+2y-3z, 证明: dfrac (partial z)(partial x)+dfrac (partial z)(pa
sin (x+2y-3z)=x+2y-3z, 则 dfrac (partial z)(partial x)+dfrac (partial z)(partial
设函数 z=z(x,y) 由方程 ^3-3xyz=8 确定,求 dfrac ({a)^2z}(a{x)^2partial y}(|)_(x-a)