X*2+X(Y-1)-（2Y*2-7Y+6）怎么变形等于（X+Y+2)(X+2Y-3

若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 1、x(x-y)(x+y)-x(x+y)^2 因式分解 (1)6(x-y)^3-3y(y-x)^2 (2)x(x-y)(a-b)-y(y-x)( 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) (1)(x^2/x)-y-x-y 1.（（y+2x)(-2x+y)+4(x+2y)^2)/3y 2.（2(x-y)^3-8(x-y）^2(x+y)+6y( [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y (x-y)的四次方(x-y)-2(x-y)²(y-x）³等于? 2(y-x)的平方-7(x-y)+6(x-y)-3(y-x)的平方 计算：(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x^8-x^7y+x^6y^2-x^5y^3+x^4y^4-x^3y^5+x^2y^-xy^7+y^8