(3a-4b)(7a-8b)+(11a+2b)(8b-7a)
=(3a-4b)(7a-8b)-(11a+2b)(7a-8b)
=[(3a-4b)-(11a+2b)]·(7a-8b)
=(3a-4b-11a-2b)·(7a-8b)
=(-8a-6b)(7a-8b)
需要乘开的话,继续追问哦~!