试说明x^3y^3-1/2x^2y+y^2-2x^3y^3+0.5x^2y+y^2+x^3y^3-2y^3-3的值与x取值无关

试说明x^3y^3-1/2x^2y+y^2-2x^3y^3+0.5x^2y+y^2+x^3y^3-2y^3-3的值与x取值无关 试说明（4x*x-7X+6Y--1）-（-2x*x+3y*y+2Y+2X)+(-6X*X+9X-Y)的值于X无关. x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² x(x-y)2-(y-x)3 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 [(3x+y)(x-y)-(2x+3y)(x-y)]*(x-y) 计算：x+2y/x-y+2x/y-x-3y/x-y 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y (Y-X)^3*(X-Y)^m+(X-Y) ^m+1*(Y-X)^2 (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 已知[(y-2x)(3x+2y)+x(y+6x)]/3y,试说明式子的值与x无关. 已知3x=4Y,5Y=6Z,求 (1)x:y:z;（2）x+y/y+z.请说明道理，