a+3b/a²-b²-a+2b/a²-b²-2a-3b/b²-a²=a+3b/a²-b²-a+2b/a²-b²+2a-3b/a²-b²=(a+3b-a-2b+2a-3b)/(a²-b²)=(2a-2b)/(a+b)(a-b)=2/(a+b)如追加其它...