几个初三的分解因式

1.4(x-y+1)+y(y-2x)
=2(2x-y)-(2y-4)+y(y-2x)
=(y-2x)(y-2)-2(y-2)
=(y-2)(y-2x-2)

2. 5x^4-8x^2-4
=(5x^2+2)(x^2-2)
=(5x^2+2)(x+ 根号2)(x- 根号2)

3. (m+n)^2-(2m+2n)(2p+n)+(2p+n)^2
=(m+n-2p-n)^2
=(m-2p)^2

4. (a^2+2a)^2-7(a^2+2a)-8
=(a^2+2a-8)(a^2+2a+1)
=(a-4)(a+2)(a+1)^2

1.4(x-y+1)+y(y-2x)
=4x-4y+4+y^2-2xy
=y^2-(2+x)2y+2(2x+2)
=(y-2)(y-2x-2)
2.5x^4-8x^2-4
=x^4-2x+1+x^4-2x+1+x^4-2x+1+x^4-2x+1+x^4-8
=4[(x^2-1)^2-1]+x^4-4
=(5x^2+2)(x^2-2)
3. (m+n)^2-(2m+2n)(2p+n)+(2p+n)^2
=(m+n)^2-2(m+n)(2p+n)+(2p+n)^2
=(m+n-2p-n)^2
=(m-2p)^2
4.(a^2+2a)^2-7(a^2+2a)-8
用十字相乘法:
a^2+2a +1
a^2+2a -8
=(a^2+2a-8)(a^2+2a+1)
=(a-4)(a+2)(a+1)^2

(2-y)(2-y+2x)