(a²-4b²/a²-4b²+a+2b)-a²+4ab-4b²=(a+2b)(a-2b)/(a+2b)(a-2b+1)-a^2+4ab-4b^2=(a-2b)/(a-2b+1)-(a-2b)^2=2/(2+1)-2^2=2/3-4=-10/3 不懂可追问满意请采纳谢谢
