若a2+b2=6,则式子(3a2-2ab-b2)-(a2-2ab-3b3)=_.

问题描述:

若a2+b2=6,则式子(3a2-2ab-b2)-(a2-2ab-3b3)=______.

∵a2+b2=6,
∴原式=3a2-2ab-b2-a2+2ab+3b3=2a2+2b2=2(a2+b2)=12.
故答案为:12