我有些数学题，公因式的，要求过程，追加70

(1)(x-y)²+4xy
=x^2-2xy+y^2+4xy
=x^2+2xy+y^2
=(x+y)^2

(2)(ab+a)+(b+1)
=a(b+1)+(b+1)
=(a+1)(b+1)

(3)a²-81
=a^2-9^2
=(a+9)(a-9)

(4)2001²-2002*2000
=2001^2-(2001+1)(2001-1)
=2001^2-(2001^2-1)
=2001^2-2001^2+1
=1

(5)(3ab-2a)/a
=a(3b-2a)/a
=3b-2a

(6)4x²y+4x²y²+x(y的立方）
=xy(4x+4xy+y^2)

(1)(x-y)²+4xy =x^2+y^2-2xy+2xy=x^2+y^2+2xy=(x+y)^2
(2)(ab+a)+(b+1)=a(b+1)+(b+1)=(a+1)(b+1)
(3)a²-81 =a^2-9^2=(a-9)(a+9)
(4)2001²-2002*2000=2001²-(2001+1)*(2001-1)=2001²-[2001²-1]
=2001²-2001²+1=1
(5)(3ab-2a)/a =a(3b-2)/a=3b-2
(6)4x²y+4x²y²+xy^3=xy(4x+4xy+y^2)