数学题，看不懂，求教

chriswendy36

  一正整数有四个质因子，其中两个相同，问该数共有几个因子？

            答案9

质因子怎么可以相同呢？是不是我的概念又混了

质因子怎么可以相同呢？是不是我的概念又混了

• The prime factors of 6 are 2 and 3 (6 = 2 × 3). Both have multiplicity 1.
• 5 has only one prime factor: itself (5 is prime). It has multiplicity 1.
• 100 has two prime factors: 2 and 5 (100 = 2² × 5²). Both have multiplicity 2.
• 2, 4, 8, 16, etc. each have only one prime factor: 2. (2 is prime, 4 = 2², 8 = 2³, etc.)
• 1 has no prime factors. (1 is the empty product)

liushuan78

答案不对吧,好象是12哦!

anchorets

答案不对吧,好象是12哦!

britney-gao

答案应该是12

2×2×3

可能是JJ叙述的问题吧

littlegirl

比如 60＝2×2×3×5 ＝2²×3×5就有4个质因子 其中2有两个

那么因子数就是各质因子的指数加1，再相乘 

60的因子个数就有（2＋1）×（1＋1）×（1＋1）＝12个

那100 = 2² × 5² 

所以，100的因子个数有 （2＋1）×（2＋1）＝9 个