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

    Possible Duplicate: Prove 0! = 1 0! = 1 from first principles Why does 0! = 1 0! = 1? All I know of factorial is that x! x! is equal to the product of all the numbers that come before it. The product of 0 and …

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

    2020年3月30日 · 1 Short Answer Yes AA -1 = A -1 A = I when the Det (A) ≠ ≠ 0 and A is a square matrix. Long Answer A matrix is basically a linear transformation applied to some space. For the sake of …

  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 $1+1=2$. Can you think …

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

    2015年5月11日 · 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 cleaner than saying …

  5. 1/1+1/2+1/3+1/4+……+1/n=?怎么个解法? - 知乎

    红线是n-1到n的割线,绿线是n处的切线 图像上显然,割线的斜率大于切线的斜率。 所以我们有割线的斜率 \dfrac {\ln \left ( n\right) -\ln \left ( n-1\right) } {n-\left ( n-1\right) } 大于切线的斜率 \left ( \ln …

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

    2010年8月30日 · The formal moral of that example is that the value of 1i 1 i depends on the branch of the complex logarithm that you use to compute the power. You may already know that 1 =e0+2kiπ 1 = …

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

    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?

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

    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】——【定义新多级列表】,找到相应 …

  9. False Proof of 1=-1 - Mathematics Stack Exchange

    2016年8月24日 · Oh, it sounds like Ivm asking those questions rhetorically. I'm not. They are very subtle and difficult questions. Ponder them and think about them. Part of the problem is that we really abuse …

  10. 为什么 1 不能被认为是质数? - 知乎

    m = p 1 a 1 p 2 a 2 p 3 a 3 p n a n . 什么意思呢? 它表示这样一个结论:对于任意的一个整数,你都能把它因数分解,而且结果是唯一的。 举个例子:1001只能被分解成7×11×13,而且你再也找不到除 …