help! 一道数学题 急

1.
x^2-y^2+a^2-b^2+2ax+2by
=x^2+2ax+a^2-y^2+2by-b^2
=(x+2)^2+(-y^2+2by-b^2)
=(x+2)^2-(y^2-2by+b^2)
=(x+2)^2-(y-b)^2
=((x+2)+(y-b))*((x+2)-(y-b))
=(x+2+y-b)*(x+2-y+b)
2.
x^3-x^2-4x+4
=(x^3-x^2)-(4x-4)
=x^2(x-1)-4(x-1)
=(x-1)(x^2-4)
=(x-1)(x+2)(x-2)
希望我的答案没错吧

x^2-y^2+a^2-2+2ax+2by
＝（x^2+2ax+a^2）-（y^2-2by+b^2）
＝（x+a）＾2-（y-b）＾2
＝（x+a+y-b）（x+a－y+b）

x^3-x^2-4x+4
＝x^2(x-1)-4(x-1)
=(x-1)(x^2-4)
=(x-1)(x+2)(x-2)

1,
x^2-y^2+a^2-b^2+2ax+2by
=(x^2+2ax+a^2)-(y^2-2by+b^2)
=(x-a)^2-(y-b)^2
=(x-a-y+b)(x-a+y-b)

2,
x^3-x^2-4x+4
=(x-1)(x^2-4)
=(x-1)(x-2)(x+2)

No.1:
x^2-y^2+a^2-b^2+2ax+2by
= (x^2+a^2+2ax)-(y^2+b^2-2by)
= (x+a)^2-(y-b)^2
= (x+a+y-b)(x+a-y-b)

No.2:
x^3-x^2-4x+4
= x^2(x-1)-4(x-1)
= (x^2-4)(x-1)
= (x+2)(x-2)(x-1)

第一题：（x+y+a-b）（x-y+a+b）
第二题：（x+2