当x=1,y=2,z=3时,求代数式3x²y-[2x²y-(2xyz-x²z)-4x
先化简后求值 求当x=1,7=2,z=3时,代数式3x^2y-[2x^2-(2xyz-x^2z)-4x^2z]-2xyz
已知xyz满足x+y+z=30,3x+y-z=50,设t=5x+4y+2z 1当t=40时,求xyz的值 2若xyz均为
已知2x+3y-4z=0,3x+4y+5z=0,且xyz≠0 .(1)分别用含有z的代数式表示x、y (2)求x+y+z
3道高数题,1,函数F(x,y,z)=(e^x) * y * (z^2) ,其中z=z(x,y)是由x+y+z+xyz=
x:y:z=2:3:4且x+y+z=18求xyz
若4x-3y-6z=0,x+2y-7z=0(xyz≠),求代数式5x²+2y²-z²/2x
方程组:x-2y+4z=0,2x+3y-3z=0...xyz不等于0,求(2x+y-z)\(2x-y+z)
已知4x-3y+z=0,x+2y-8z=0,xyz不等于0,求x+y-z/x-y+2z的值
已知 x,y,z都是正实数,且 x+y+z=xyz 证明 (y+x)/z+(y+z)/x+(z+x)/y≥2(1/x+1
已知x-2y+z=0,3x+6y-z=0(xyz≠0),求2x²+y²/x²+y²
若x-y=6,xy=-8,求代数式(x+y+z)²+(x-y-z)(x-y+z)-2·z(x+y)的值
4X—3Y—6Z=0 X+2Y—7Z=O(XYZ不等于0)求代数式X-y+z除以x+y+z的值