2013a/(a²-2a+1)÷(a+1)/(a²-1)+1
=2013a/(a-1)²×(a-1)(a+1)/(a+1)+1
=2013a/(a-1)×(a+1)/(a+1)+1
=2013a+a-1/(a-1)
=(2014a-1)/(a-1)
有没有错?