(a+2b)(a-2b)(a-2b)²-4ab
=(a²-4b²)(a-2b)²-4ab
=(1-1/25)(1-1/5)²-2/5
=24/25×16/25-2/5
=(384-250)/625
=134/625лл不客气,如对你有帮助,请采纳,谢谢