7a-8b=5,求(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
问题描述:
7a-8b=5,求(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
答
(3a-4b)(7a-8b)-(11a-12b)(8b-7a)=(7a-8b)(3a-4b+11a-12b)
=5(14a-16b)=5*10=50