x=3y-2.①y=2x-1.②

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x^2-y分之y(x-y)-x(x+y)除以x+y分之x^2+y^2.其中x=2,y=-1.先化简再求值. 用代入法做方程 1.{2x-y=8 ① x+3y=-3 ② 2.{2x-3y=1 ① 3x+2y=8 ②3.{(x+y)/2-(x-y)/6=1 ① 3x+4y=0 ②4.{(x+y)/2+(x-y)/3=6 ① 4(x+y)-5(x-y)=2 ②尽快 ..求你们了 2(x+y)-3(X-y)=3①4(X+y)+3(x-y)=15② {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? x=3y-2.①y=2x-1.② 结果用幂的形式表示:1.（x-y）^2(y-x)= 2.(x-y)^2(y-)^2= 3.(x-y)^2(y-x)^3= 4.(x-y)^3(y-x)= (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 1.用代入解法解下列方程组：①x+2y=-1,3x-2y=8; ②x-y=4,3x+y=16； ③x-y=8,3x+y=12. 解方程组：1.{x+y=4①,2x-y=5 ② 2.{2x+3y=4①,5x+6y=7②3.{3分之x+y+2分之x-y=6 ,3（x+y)-2（x-y)=284.{5分之x=2分之y ,3x-2y=225.{2x-3y/4+2（x+2y）=1,3（2x-3y)/4-x+2y/5+4=0 (x+y)(2x-3y)=? 1.(2x-3y)(2x+3y)=2.（5x+3y）（3y-5x）3.（x-3y）（-x+3y）=4.（x+y-z）²= 先化简再求值:(x+y)(x-y)+(x^2-2xy+y^2)-(x^2y)^3÷(x^2y)^2,其中x=1,y=2. 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y²