若a+b=3,ab=-2,求(5a-5b-ab)-(4a-6b-3ab)
问题描述:
若a+b=3,ab=-2,求(5a-5b-ab)-(4a-6b-3ab)
答
(5a-5b-ab)-(4a-6b-3ab)
=5a-5b-ab-4a+6b+3ab
=a+b+2ab
=3-2x2
=-1