(3a-4b)(7a-8b)+(11a-12b)(8b-7a),其中a==2,b=1
(3a-4b)(7a-8b)-(11a-12b)(7a-8b)=(7a-8b)(3a-11a-4b+12b)=(7a-8b)(-8a+8b)=8(7a-8b)(b-a)
当a==2,b=1时,原式=8(14-8)(1-2)=8×6×-1=-48
(3a-4b)(7a-8b)+(11a-12b)(8b-7a),其中a==2,b=1
(3a-4b)(7a-8b)-(11a-12b)(7a-8b)=(7a-8b)(3a-11a-4b+12b)=(7a-8b)(-8a+8b)=8(7a-8b)(b-a)
当a==2,b=1时,原式=8(14-8)(1-2)=8×6×-1=-48