[（4a²-4a)/(a²2a+1)]÷[a+1/(a-1)-(a-1)/(a+1)]×[1/(3a+3）]

[（4a²-4a)/(a²2a+1)]÷[a+1/(a-1)-(a-1)/(a+1)]×[1/(3a+3）]
[（4a²-4a)/(a²2a+1)]÷[a+1/(a-1)-(a-1)/(a+1)]×[1/(3a+3）]

[（4a²-4a)/(a²2a+1)]÷[a+1/(a-1)-(a-1)/(a+1)]×[1/(3a+3）]
原式=(4a(a-1)/2aaa+1)x（(a+1)(a-1)/4a）x（1/3(a+1)）
=(aa+1+2a)/(6aaa+3)