x^2y-y^2z+xz^2-x^2z+xy^2+yz^2-2xyz因式分解,要求用主元法,分别给出以x为主元,以y为主元,z为主元的三种方法

(2X+Z-Y)/(X^2-XY+XZ-YZ)-(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-yz+xy) 已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3 求(2X+Z-Y)/(X^2-XY+XZ-YZ)-(2X+Y+Z)/(X^2+XY+XZ+YZ) 代数 x^-y^/ x^-(y-z)^ 除以 x^+2xy+y^/(x-y)^-z^ 乘 x^+xy-xz/x^-xy 若x>y>z>0,求证：x-z+27/[(x+z)y-xz-y^2]≥9 2yz/x+2xz/y+2xy/z≥2x+2y+2z xz+xy^2=e^z 求&z/&x ,&z/&y (x^2+yz)/(x^2+x(y-z)-yz)+(y^2-xz)/(y^2+y(x+z)+zx)+(z^2+yx)/(x^2-z(x-y)-yx)最后一项应为：(z^2-xy)/(z^2+z(y-x)-xy) x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2 =[x(y+z)-y(x-z)]^2 =(xz+yz)^2 =z^2(x+y)^2 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 若x:y=3:2, y²=xz求x:y:z的值 已知XY+X/X+Y+1=2 XZ+2X/X+Z+2=3 (Y+1)(Z+2)/Y+Z+3=4 求X+Y+Z的值已知(XY+X)/(X+Y+1)=2 (XZ+2X)/(X+Z+2)=3 [(Y+1)(Z+2)]/(Y+Z+3)=4 求X+Y+Z的值 由隐函数xz=ln(z+y^2)确定了z=z(x,y) 求全微分dz x,y,z属于正实数,x-2y+3z=0求y^2/xz的最小值 x,y,z属于R,x-2y+3z=0,y^2/xz的最小值是? 已知x,y,z属于R+,x-2y+3z=0,则(y平方)/(xz)的最小值为? 已知x,y,z为正实数,满足x-y+2z=0,求y²/(xz)的最小值