2x+3y=9 x+y=20

3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 2x+3y=9 x+y=20 (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) (x+y)(2x-3y)=? 9y=3x-(x-1),4(x+y)-(2x+4)=8y 5x=3y,(2x+y)的平方=5x(x+y)+9 3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8 3y=2x y/3=x/2 12/x=9/y y/x=?y/x=?x/y=? 根据3（x+y)-2(x-y)=11,4(x+y)+3(x-y)=9可得出x+y= ,x-y= 已知2x-y/x+2y=3,求2(2x-y)/x+2y-9(x+2y)/2x-y+3的值. 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=