2a-(a+1)+a的平方-1的和/a-1

问题描述:

2a-(a+1)+a的平方-1的和/a-1

2a-(a+1)+(a²-1)/(a-1)
=2a-(a+1)+(a+1)(a-1)/(a-1)
=2a-(a+1)+(a+1)
=2a