化简求值：(3aa2−1−1a2−1)+aa−1÷a2+aa2−2a+1−1，选一个你喜欢a值代入并求值．

Question

化简求值：((3a)/(a2−1)−(1)/(a2−1))+(a)/(a−1)÷(a2+a)/(a2−2a+1)−1，选一个你喜欢a值代入并求值．

Answer 1

原式=((3a−1)/(a2−1))+(a)/(a−1)×((a−1)2)/(a(a+1))−1
=(a2+a)/(a2−1)−1
=(1)/(a−1)，
∵分式的分母不为0，
∴a（a²-1）≠0，
∴a≠0，-1，1，
∴当a=2时，原式=(1)/(a−1)=(1)/(2−1)=1．