若7a-8b=5.求(3a-4b)(7a-8b)-(11a-12b)(8b-7a)的值_数学解答

若7a-8b=5.求(3a-4b)(7a-8b)-(11a-12b)(8b-7a)的值

人气：169 ℃　时间：2020-03-15 14:55:25

解答

(3a-4b)(7a-8b)-(11a-12b)(8b-7a)
=(7a-8b)(3a-4b+11a-12b)
=(7a-8b)(14a-16b)
=2(7a-8b)²
=2×5²
=50