问几道初中代数题,初中数学优秀者请进

1(1).b并不等于a，而且答案应该为b-a
(2).应该为1/（x+y)
2.等于-x^2y
3.中间应该为减号吧
原式=（3x+3y)^2-(2x-2y)^2=(5x+y)*(5Y+x)

1.
(1)
(a^2-2ab+b^2)÷(b-a)
=(a-b)^2÷(b-a)
=(a-b)^2÷[-(a-b)]
=-(a-b)

(2)
(x^2+2xy+y^2)÷(x+y)^3
=(x+y)^2÷(x+y)^3
=1/(x+y)

2.
(xy-x^2)÷[(x-y)/xy]
=x(y-x)÷[(x-y)/xy]
=-x(x-y)÷[(x-y)/xy]
=-x(x-y)*[xy/(x-y)]
=-x^2y

3.
9(x+y)^2-4(x-y)^2
=[3(x+y)-2(x-y)][3(x+y)+2(x-y)]
=[(3x+3y)-(2x-2y)][(3x+3y)+(2x-2y)]
=(3x+3y-2x+2y)(3x+3y+2x-2y)
=(x+5y)(5x+y)

1.下列各式对不对，如果不对，应该怎样改正？
(1) (a^2-2ab+b^2)÷(b-a)=a-b ------这样消掉 a-b 要小心，因可能a=b。
(2) (x^2+2xy+y^2)÷(x+y)^3=x+y -----1/（x+y），且 不可以 x=y.

2.计算 (xy-x^2)÷(x-y / xy) =-(x^2)*y 且 不可以 x=y.

3.分解因式,请写出详细过程。
9(x+y)^2-4(x-y)^2 =(5x+y)*(x+5y)

(1) (a^2-2ab+b^2)÷(b-a)=b-a
(2) (x^2+2xy+y^2)÷(x+y)^3=1/x+y
2.计算
(xy-x^2)÷(x-y / xy)=-x^2y
3.分解