x^2+y^2+z^2>=yz+xz+xy证明
(2X+Z-Y)/(X^2-XY+XZ-YZ)-(Y-Z)/(X^2-XY-XZ+YZ)
设x,y,z∈R+,xy+yz+xz=1,证明不等式:(xy)^2/z+(xz)^2/y+(yz)^2/x+6xyz≥x
2^x=5^y=10^z证明xy=xz=yz
2^x=5^y=10^z证明xy=xz+yz
求(2X+Z-Y)/(X^2-XY+XZ-YZ)-(2X+Y+Z)/(X^2+XY+XZ+YZ)
化简(2x-y-z/x^2-xy-xz+yz)+(2y-x-z/y^2-xy-yz+xz)+(2x-x-y/z^2-xz
x^2+y^2+xy=25/4,x^2+z^2+xz=169/4,y^2+z^2+yz=36,求xy+xz+yz
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
x^2+y^2+z^2=2,xy+yz+xz的范围
如果1=xy/x+y,2=yz/y+z,3=xz/x+z,则x的值?
证明yz(2x+y+z)dx+xz(x+2y+z)dy+xy(x+y+2z)dz为全微分,并求原函数
一道初二分式计算题(2X+Z-Y)/(X^2-XY+XZ-YZ)-(2X+Y+Z)/(X^2+XY+XZ+YZ)