1.(2a+b+1)(2a-b-1)（运用完全平方）
=4a²-（b+1）²
=4a²-b²-2b-1
2.3(a+1)^2-5(a+1)(a-1)+2(a-1)^2
=[3(a+1)-2(a-1)][(a+1)-(a-1)]
=2(a+5)
=2a+10