（1）多项式2ab-ab的2次方+3与2ab的2次方+3ab-1的差为?（二）化简：（1）(2a²-1+2a)

1
2ab-ab²+3-(2ab²+3ab-1)
=2ab-ab²+3-2ab²-3ab+1
=-3ab²-ab+4
2
(2a²-1+2a)-3(a-1-a²)
=2a²-1+2a-3a+3+3a²
=5a²-a+2