a²+2a-1=0a²+2a=1a²+2a+1=2(a+1)²=21/(a+1)-(a+3)/(a²-1)×（a²-2a+1)/(a²+4a+3)=1/(a+1)-(a+3)/[(a+1)(a-1)]×(a-1)²/[(a+1)(a+3)]=1/(a+1)-(a-1)/(a+1)²=[a+1-(a-1)...