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

    2015年5月11日 · 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 …

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

    2020年6月13日 · 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?

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

    2013年1月15日 · 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 …

  4. 知乎 - 有问题,就会有答案

    知乎,中文互联网高质量的问答社区和创作者聚集的原创内容平台,于 2011 年 1 月正式上线,以「让人们更好的分享知识、经验和见解,找到自己的解答」为品牌使命。

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

    2010年8月30日 · 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 …

  6. If $A A^{-1} = I$, does that automatically imply $A^{-1} A = I$?

    2020年3月30日 · This is same as AA -1. It means that we first apply the A -1 transformation which will take as to some plane having different basis vectors. If we think what is the inverse of A -1 …

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

    2022年6月28日 · 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 …

  8. 知乎 - 知乎

    知乎是一个中文互联网高质量问答社区和创作者聚集的原创内容平台,提供知识共享、互动交流和个人成长机会。

  9. 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。

  10. 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, …