若a+b=3,ab=-2,则(4a-5b-3ab)-(3a-6b+ab)=______.
问题描述:
若a+b=3,ab=-2,则(4a-5b-3ab)-(3a-6b+ab)=______.
答
∵a+b=3,ab=-2,
(4a-5b-3ab)-(3a-6b+ab)
=4a-5b-3ab-3a+6b-ab
=a+b-4ab
=3-4×(-2)
=11,
故答案为:11.
答案解析:先去括号,再合并同类项,把a+b和ab的值代入求出即可.
考试点:整式的加减—化简求值.
知识点:本题考查了整式的加减和求值,用了整体代入思想,即把a+b和ab当作一个整体来代入.