1999 Multiple-choice Questions in Mathematics Series for Postgraduate Entrance Examination
The reason why we choose N 1=N- 1 is that we must change the previous sentence from n≥N to n > a certain number (because you see the definition of sequence limit, there must be a number greater than a number, and it cannot be greater than or equal to it) and greater than or equal to N 1 and greater than n1-65438.