Question

已知a-b=5,ab=-1,求（2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)的值

一道数学题

Answer 1

由已知可得：
（2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)
=2a+3b-2ab-a-4b-ab-3ab-2b+2a
=3a-3b-6ab
=3(a-b)-6ab
=3×5-6×(-1)
=21

Answer 2

（2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)
=2a+3b-2ab-a-4b-ab-3ab-2b+2a
=3a-3b-5ab=3(a-b)-6ab=15-(-6)=21

Answer 3

(2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)=3a-3b-6ab=3(a-b)-6ab=3*5-6*(-1)=21

Answer 4

（2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)
=2a+3b-2ab-a-4b-ab-3ab-2b+2a
=3a-3b-6ab
=3(a-b)-6ab
=3*5-6*(-1)
=15+6
=21

Answer 5

答案是21