6x^2-12xy+6y^2/3x-3y 谢谢帮帮忙,要理由!1

1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y) 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) x^2-xy-6y^2+3xy+y+2 9xy(x-y)(x+1)-3y(x-y)(3x+2y)+6y的平方(x-y)(x+1),因式分解 先化简,再求值：（6x-2y)*3/2xy^2-(xy-3)(xy+1)-(3x-4y)(3x+4y)+(2x-1/2y 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y (1)已知x+y=6,xy=-3,x^2y+xy^2= 已知1/x=1/y=6,则3x-2xy+3y/3xy+x+y=? 2(x+y)-3(x-y) =1 6(x+y)+7(x-y)=51大神们帮帮忙 化简分式方程:x*x-xy-y*y/x*x-3x-6y+2xy x^8-x^7y+x^6y^2-x^5y^3+x^4y^4-x^3y^5+x^2y^-xy^7+y^8