—2x+5(x+2y)—(x—3y) 3x+2(y-x)-(-x-4y) (x-2y)-(y-3—2x+5(x+2y)—(x—3y) 3x+2(y-x)-(-x-4y)(x-2y)-(y-3x)

—2x+5(x+2y)—(x—3y) 3x+2(y-x)-(-x-4y) (x-2y)-(y-3—2x+5(x+2y)—(x—3y) 3x+2(y-x)-(-x-4y)(x-2y)-(y-3x) 若x+y分之x-y=3,求式子x+y分之5(x-y)—2(x-y)分之x+y的值 若x-y分之x+y=3,求式子x+y分之5(x-y)—2（x-y）分之x+y的值 3x—y=5 ,5x+2y=12 ,x=?y=? 若将x-y看成一个整体,则化简(x-y)^2—3(x-y)-4(x-y)^2+5(x-y) 先化简,再求值.其中x=-2,y=二分之一 {(x+y)2—(x+y)(x+3Y)—5Y平方}除2y 化简:5(x-y)+2(x+y)-3(x-y) (X—3y)—(y—2X) 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x(x-y)2-(y-x)3 计算：(x—y)^7÷(y—x)^6+(—x—y)^3÷(x+y)^2 (2x-3y)-(5x-y) (2X-3y)-(5x-y) (2x-5y)(3x+y) 3(x+y)—4(x—y)=4 { (x+y)/2+(x—y)/6=1 (2x+y)²+(x+3y)(x-3y)-x(5x+8y)因式分解 因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+（x-3y)(x-5y)+(x-2y)(x-4y) 2(x-y)/3—x+y/4=1 6(x+y)—4(2x-y)=16