若 x/2=y/3=z/4 求 xy+yz+xz / x²+y²+z² 的值

若x+y=4,x^3+y^3=(x+y)(x^2-xy+y^2)z,求x^3+12xy+y^3的值. 若|x-3|+|y+2|+|2z+1|=0,求(xy-yz)(y-x+z) 若：X^2-4X+Y+6Y+√ Z-3+13=0求（xy)^z的值 已知4x-3y=6z 2x+4y=14z 求2xy/x^+y^ 已知4x-3y=6z 2x+4y=14z 求2xy/x^+y^ 若x/3=y=z/4,且xy+xz+yz=76,求2x*x+12y*y+9z*z的值 已知3x－y+2z=x+2y+3z=0,求（3x^－xy+2y^)/(2x^+4xy+y^)值? 已知XY=2(X+Y),YZ=4(Y+Z),ZX=5(Z+X),求X,Y,Z已知XY=2(X+Y),YZ=4(Y+Z),ZX=5(Z+X),求X,Y,Z 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 若x+y=6,xy=-8,求代数式(x+y-z)^2+(x+y-z)(x+y+z)-2·z(x-y) 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 方程组xy/x+y=2 yz/y+z=4 zx/x+z=5 求x,y,z 已知｛X-3Y+7z=0,x-2y+4Z (xy不等于0）.求X:Y:ZX-2Y+4Z=0 若f(x,y)=xy,g(x,y,z)=x+y-z.求f(-1/3,1/2)-g(5,-3,4)的值 若x-3=y-2=z-1,求x^+y^+z^-xy-yz-xz的值,若x-3=y-2=z-1,求x^+y^+z^-xy-yz-xz的值 若|x-3|+|y+z|+|2z+1|=0,求XY-YZ的值 若｜x-3｜+｜y+z｜+｜2z+1｜=0,求xy-yz的值 4x-3y-3z=0x-3y-z=0（1）求x：z（2）求x：y：z（3）求xy+2yz/x方+y方-z方