化简运算:(2xy-3x^2y^2)-(5x+3xy-y^2x^2) (5y+3x-15z^2)-(12y+78x+z^
化简(y-x)(z-x)/(x-2y+z)(x+y-2z)+(z-y)(x-y)/(xy-2z)(y+z-2x)+(x-
5yz/(y+z)=6,4xy/(z+x)=3,3xy/x+y=2
1.(x+y-z)+(x-y+z)-(x-y-z) 2.2x-(3x-2y+3)-(5y-2)
x+y=-10,xy方=-81,求3[-(x+y)+2xy方-z]-2[(x+y)-xy方+z]-5[-3(x+y)-z
已知实数x,y,z满足x-y=5,z^2=-xy-y-9,求x-2y+3z的值
已知实数x.y.z满足x+y=5及z的2次方=xy+y-9则x+2y+3z=?
已知x y z 满足x+y=5,z²=xy+y-9,求x+2y+3z的值
已知实数x,y,z,满足x+y=5,z²=xy+y=9,求x+2y+3Z的值
若x/3=y/2=z/5,且xy+yz+zx=93,求9x*x+12y*y+2z*z的值.
实数x、y、z满足x=6-3yx+3y-2xy+2z
已知x>0,y>0,z>0,证明x^3/(x+y)+y^3/(y+z)+z^3/(z+x)≥(xy+xz+yz)/2
(2X+Z-Y)/(X^2-XY+XZ-YZ)-(Y-Z)/(X^2-XY-XZ+YZ)