6a²-2ab-2(3a²+ab)（
=6a²-2ab-6a²-2ab
=-4ab化简5ab²-[2a²b-2(a²b-2ab²)(过程)5ab²-[2a²b-2(a²b-2ab²)=5ab²-（2a²b-2a²b+4ab²）=5ab²-4ab²=ab²