[求助]TT GWD-4-15

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Q15:

If n is a positive integer and r is the remainder when (n – 1)(n + 1) is divided by 24, what is the value of r?

(1)     2 is not a factor of n.

(2)     3 is not a factor of n.

答案是C我选E，请指教

zyzcdcdcd

自己顶....诚心求教

zyzcdcdcd

谢谢~~！原来我题目看错了.....