Question

(a+b)^4-(a+b)^2x^2(x-y)+y^2(x-y)(7m+3n)^2-(5m+7n)^2

Answer 1

1、(a+b)^4-(a+b)^2

=＜（a+b)^ 2+a+b)＞＜（a+b)^2-a-b＞

=(a+b)(a+b+1)＜（a+b)^2-a-b＞

2、x^2(x-y)+y^2(x-y)

=(x-y)(x^2-y^2)

=(x-y)(x+y)(x-y)

=(x+y)(x-y)^2

3、(7m+3n)^2-(5m+7n)^2

=(7m+3n+5m+7n)(7m+3n-5m-7n)

=(12m+10n)(2m-4n)

=4(6m+5n)(m-2n)