若1/x-1/y=3,则2x-3y-2y/x-2xy-y的值为( )

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） 若x,y满足|2x-y-3|+|3x+2y+1|=0,则x= y= 若x,y满足|x-y+1|+(x+y+3)^2=0则x^2-y^2= (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 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 (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 若x=-1/4,能否确定代数式(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)的值? 若变量x,y满足约束条件{x>=-1;y>=x;3x+2y x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值