初一数学把下列因式分解 我急啊!`~~~~~~`~`~

1.(x+2)(x+3)+x^2-4
2.(x+y)^2-4(x+y-1)
3.4x(x+y)+y^2
4.(x^2-y^2)(x+y)-(x-y)^3
5.x^2-6+9
6.设x+y=2,求(1/2)^2+xy+(1/2)y^2的值．
7.已知5x^2-4xy+y^2-2x+1=0，求3+(y/2)^2006的值．

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

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

3.4x(x+y)+y^2
=4x^2+4xy+y^2
=(2x+y)^2

4.(x^2-y^2)(x+y)-(x-y)^3
=(x-y)(x+y)(x+y)-(x-y)^3
=(x-y)(x+y)^2-(x-y)(x-y)^2
=(x-y)((x+y)^2-(x-y)^2)
=(x-y)(x+y+x-y)(x+y-x+y)
=(x-y)(2x)(2y)
=4xy(x-y)

5.x^2-6x+9
=(x-3)^2

6.设x+y=2,求(1/2)x^2+xy+(1/2)y^2的值．
(1/2)x^2+xy+(1/2)y^2
=1/2(x^2+2xy+y^2)
=1/2(x+y)^2
=1/2*2^2
=2

7.已知5x^2-4xy+y^2-2x+1=0，求3+(y/2)^2006的值．
5x^2-4xy+y^2-2x+1=0
4x^2-4xy+y^2+x^2-2x+1=0
(2x-y)^2+(x-1)^2=0
2x-y=0
x-1=0
所以
x=1
y=2
3+(y/2)^2006
=3+(2/2)^2006
=3+1^2006
=3+1
=4

1.（x+2）(2x+1)
2.(x+y-2)^2
3.(2x+y)^2
4.4xy(x-y)
5.(x-3)^2
6.1/2(x+y)^2
7.(2x-y)^2+(x-1)^2=0
x=1,y=2
3+(y/2)^2006=3+1=4