(3a+4b)(7a-8b)+(11a+2b)(8b-7a)
=(3a+4b)(7a-8b)-(11a+2b)(7a-8b)
=(7a-8b)[(3a+4b)-(11a+2b)]
=(7a-8b)(-8a+2b)
=-2(7a-8b)(2a-b)
这题我改了一下,不知是不是这样,请对一下题呀.