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  1. Formal proof for $ (-1) \times (-1) = 1$ - Mathematics Stack …

    Jun 13, 2020 · Is there a formal proof for $(-1) \\times (-1) = 1$? It's a fundamental formula not only in arithmetic but also in the whole of math. Is there a proof for it or is it just assumed?

  2. What is the value of $1^i$? - Mathematics Stack Exchange

    Aug 30, 2010 · There are infinitely many possible values for $1^i$, corresponding to different branches of the complex logarithm. The confusing point here is that the formula $1^x = 1$ is …

  3. Why is $1/i$ equal to $-i$? - Mathematics Stack Exchange

    May 11, 2015 · 11 There are multiple ways of writing out a given complex number, or a number in general. Usually we reduce things to the "simplest" terms for display -- saying $0$ is a lot …

  4. 1/1+1/2+1/3+1/4+……+1/n=?怎么个解法? - 知乎

    两边求和,我们有 ln (n+1)<1/1+1/2+1/3+1/4+……+1/n 容易的, \lim _ {n\rightarrow +\infty }\ln \left ( n+1\right) =+\infty ,所以这个和是无界的,不收敛。

  5. abstract algebra - Prove that 1+1=2 - Mathematics Stack Exchange

    Jan 15, 2013 · Possible Duplicate: How do I convince someone that $1+1=2$ may not necessarily be true? I once read that some mathematicians provided a very length proof of $1+1=2$. Can …

  6. 为什么 1 不能被认为是质数? - 知乎

    质数就是“只能被1和它本身整除”的自然数。 然而,我们必须在此基础之上增加一条警告,宣称数字1不是质数,这简直就像马后炮一样。

  7. factorial - Why does 0! = 1? - Mathematics Stack Exchange

    Intending on marking as accepted, because I'm no mathematician and this response makes sense to a commoner. However, I'm still curious why there is 1 way to permute 0 things, …

  8. Why is $1$ not a prime number? - Mathematics Stack Exchange

    Jun 28, 2022 · 49 actually 1 was considered a prime number until the beginning of 20th century. Unique factorization was a driving force beneath its changing of status, since it's formulation is …

  9. 1/8, 1/4, 1/2, 3/4,7/8英寸分别是多少厘米? - 知乎

    把1英寸分成8等分: 1/8 1/4 3/8 1/2 5/8 3/4 7/8 英寸。 This is an arithmetic sequence since there is a common difference between each term. In this case, adding 18 to the previous term in the …

  10. Word,插入多级列表,但是改了1.1,第二章的2.1也变成1.1,随着 …

    注1:【】代表软件中的功能文字 注2:同一台电脑,只需要设置一次,以后都可以直接使用 注3:如果觉得原先设置的格式不是自己想要的,可以继续点击【多级列表】——【定义新多级 …