3A-2(2B+2分之A+B)
=3(a³-3a²+a)-2[2﹙-a³+a²-4a-5﹚+½﹙-2a²-3a-5﹚]
=3a³-9a+3a+4a³-4a²+16a+20+2a²+3a+5
=7a³-11a²-22a+25