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

    Jun 28, 2022 · 50 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 …

  2. 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?

  3. what is 1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + 1/7 - 1/8 +1/9

    Nov 28, 2019 · Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and …

  4. Series expansion: $\frac {1} { (1-x)^n}$ - Mathematics Stack …

    Dec 2, 2024 · What is the expansion for $(1-x)^{-n}$? Could find only the expansion upto the power of $-3$. Is there some general formula?

  5. 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 …

  6. How can 1+1=3 be possible? - Mathematics Stack Exchange

    Feb 3, 2021 · So that's the "proof". The failure is at step 5, where you say that pq = pr p q = p r implies that q = r q = r; that's true only if you know p p is nonzero. For instance 0 ⋅ 5 = 0 ⋅ 7 0 5 …

  7. algebra precalculus - Prove $0! = 1$ from first principles ...

    How can I prove from first principles that $0!$ is equal to $1$?

  8. elementary number theory - Prove $ x^n-1= (x-1) (x^ {n-1}+x^ {n …

    Aug 17, 2014 · 13 So what I am trying to prove is for any real number x and natural number n, prove xn − 1 = (x − 1)(xn−1 +xn−2 + ⋯ + x + 1) x n 1 = (x 1) (x n 1 + x n 2 + + x + 1) I think …

  9. calculus - Proof of $\lim_ {x\to a}f^ {g}=e^ {\lim_ {x\to a} { (f-1)g ...

    Oct 27, 2016 · There is a general formula for indeterminate form 1∞ 1 ∞ which I'm looking for a proof which is also used here. (picture) Given

  10. 如何定义什么是 1? - 知乎

    May 9, 2018 · 我们可以从数学上证明 1+1=2,但是如何定义 1 是什么。如果说是 0 的后继数,那又如何定义 0 呢?