已知a-b=3,a×b=-3,求代数式(2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)的值,

问题描述:

已知a-b=3,a×b=-3,求代数式(2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)的值,

(2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)
=2a+3b-2ab-a-4b-ab-3ab-2b+2a
=2a+2a-a+3b-4b-2b-2ab-ab-3ab
=3a-3b-6ab
=3(a-b)-6ab
=3*3-6*(-3)
=9+18
=27

(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
=9+18
=27