帮忙做几道因式分解,要过程,谢谢.

题目

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)
144a的四次方-256a²
4（m+n)²-49m²(9m+2n)(2n-5m)

答案

(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)