2002+p係質數,2002-p又係質數
p最小值?
點計?
更新1:
P係質數!!!! 有冇公式計到呢條數?
更新2:
好似冇人問我講咩 我係話 p 同 2002+p同2002-p 3個數全部都係質數!!!!!!! 唔係3個之中有1個係質數!!!!!!!
質數問題(p,2002+p,2002-p)
回答 (2)
2009-05-06 1:22 am
✔ 最佳答案
有的三個數
2002+p p 2002-p
若p係3n(n係一個整數)
係3n+1(n係一個整數)
係3n+2(n係一個整數)
2002+3n 3n 2002-3n
2002+3n+1 3n+1 2002-(3n+1)
2002+3n+2 3n+2 2002-(3n+2)
以上3個情況都必有一個係3ge倍數
因此3ge倍數中得3係質數
因此2002+p p 2002-p中是但一個係3
2002+p不可能是3
如果p=3,2005不是質數
因此只有2002-3
姐係1999
2009-05-01 5:00 am
By trial and error method:
p = 1, 2002 - 1 = 2001 = 3 x 667
p = 2, 4, 6, 8 and 0 are all even numbers.
p = 3, 2002 + 3 = 2005 = 5 x 401.
p = 5, 2002 + 5 = 2007 = 3 x 669.
p = 7, 2002 - 7 = 1995 = 5 x 399.
p = 9, 2002 + 9 = 2011, 2002 - 9 = 1993, both are prime numbers, so p = 9.
p = 1, 2002 - 1 = 2001 = 3 x 667
p = 2, 4, 6, 8 and 0 are all even numbers.
p = 3, 2002 + 3 = 2005 = 5 x 401.
p = 5, 2002 + 5 = 2007 = 3 x 669.
p = 7, 2002 - 7 = 1995 = 5 x 399.
p = 9, 2002 + 9 = 2011, 2002 - 9 = 1993, both are prime numbers, so p = 9.
收錄日期: 2021-04-25 22:37:52
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090430000051KK01367