帮忙做几道因式分解,要过程,谢谢.

(x+y-2)(x-y+2)+(y-x+2)(y-x-2)
=(x+y-2)(x-y+2)-(x-y+2)(y-x+2)
=(x-y+2)(x+y-2-(y-x+2))
=(x-y+2)(x+y-2-y+x-2)
=(x-y+2)(2x-4)
=2(x-2)(x-y+2)
144a^4-256a^2
=16a² * (9a² - 16)
=16a² (3a + 4)(3a - 4)
4(m+n)² - 49m²
=(2(m + n)+7m) * (2(m + n)-7m)
=(9m + 2n) * (2n - 5m)

1.x^4+x^2+2ax+1-a^2 = x^4+2x^2+1 -(x^2-2ax+a^2)=(x^2+1)^2-(x-a)^2=(x^2+x+a+1)(x^2-x-a+1) 2.4x^2-4x-y^