-1又2/3ab³+2a³b-4又1/2a²b-ab³-1/2a²b-a³b
=5ab³/3+2a³b-9a²b/2-ab³-a²b/2-a³b
=ab(5b²/3+2a²-9a/2-b²-a/2-a²)
=ab(2b²/3+a²-5a)