设z=x^4+3x^2y^2+y^5x^3-xy^3,求全微分.

设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 设z≠0 x、y、z 满足4x-7y-5z=0 2x-y-z=0 求x：y 设z≠0,x、y、z满足4x-7y-5z=0、2x-y-z=0,求x:y 设x,y满足约束条件 分别求 1.Z=6x+3y 2.Z=2x-y 3.Z=-x+y的最大值 x-4y≤-3 3x+5y≤25 x≥3设x,y满足约束条件 分别求 1.Z=6x+3y 2.Z=2x-y 3.Z=-x+y的最大值x-4y≤-33x+5y≤25x≥3 设z={x-y x≥2y,x/4+y/2 x (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuaihuajian x+y=5 2x+3y-z=9 x-y+z=4 设x：y：z：=2：3：5,且满足3x-3y+z=4,求2x+3y-4z的值? 设K法解, 已知x : y : z =3 : 4 : 5 且2x+3y+z=46,求x+y+z的值谢谢 设x,y.z为实数,2x.3y.4z是等比数列,1/x,1/y.1/z是等差数列,则(x/z)+(z/x)是多少? 设X+Y+Z=0求X^3+X^2Z-XYZ+Y^2Z+Y^3的值 设x+y+z=11求函数u=2x*x+3y*y+z*z的最小值 设z=2x+y式中变量x,y同时满足x-4y 设Z=X+Y,其中X,Y满足X+2Y>=0,X-Y 选择.设y=2x-1,z=3y ,则x+y+z等于（ ）1.9x-1 2.2x 3.9x-3 4.9x-4 (4x-2y-z)-{5x-[8y-2z-(x+y)]-2(3y-10z)}=?好难啊 x/2=y/3=z/5 x+3y-z/x-3y+z