A. x＞y＞z
B. x＞z＞y
C. y＞x＞z
D. y＞z＞x
[单选题]已知实数x，y，z满足x2＋y2＋z2－2x＋4y－6z＋14＝0，则x＋y＋z＝（）。A . 2B . 3C . 4D . 5
(x,y,z)=(x)^3+4(y)^3+4(z)^2，则(x,y,z)=(x)^3+4(y)^3+4(z)^2（）。(x,y,z)=(x)^3+4(y)^3+
2x+3y+Z=4X-2y+4z=-5(2)3x+8y-2z=134x-y+9z=-62x+3y+Z=4X-2y+4z=-5(2)3x+8y-2z=134x-y
设(x,y,z)=(x)^2+(y)^3+z,求(x,y,z)=(x)^2+(y)^3+z,在点(x,y,z)=(x)^2+(y)^3+z,处沿方向(x,y,z
求函数y=√x-3sinx+log3x+cosπ/的导数A.y=√x-3sinx+log3x+cosπ/B.y=√x-3sinx+log3x+cosπ/C.y=
设sin (x+2y-3z)=x+2y-3z，证明sin (x+2y-3z)=x+2y-3z.设，证明.
2x+y-z+W=1(4){3x-2y+z-3w=4x+4y-3z+5w=-22x+y-z+W=1(4){3x-2y+z-3w=4x+4y-3z+5w=-2
(4) ) 2x+y-z+w=1 3x-2y+z-3w=4 x+4y-3z+5w=-2 .
设函数(x,y,z)=2(x)^3y-3(y)^2z在点(x,y,z)=2(x)^3y-3(y)^2z处梯度的模为(x,y,z)=2(x)^3y-3(y)^2z
sin (x+2y-3z)=x+2y-3z, 则 dfrac (partial z)(partial x)+dfrac (partial z)(partial