время, часовой пояс

如何定义什么是 1？ - 知乎
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？
1-1+1-1+1-1+1. . . 这个无穷数列的值是什么？如何证明？ - 知乎
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。
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 n\right) '=\dfrac {1} {n} 。我们有 \ln n-\ln \left ( n-1\right) >\dfrac {1} {n} 我们累加 \sum \left ( \ln n-\ln \left ( n-1\right
知乎 - 知乎
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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?
False Proof of 1=-1 - Mathematics Stack Exchange
False Proof of 1=-1 [duplicate] Ask Question Asked 9 years, 7 months ago Modified 9 years, 7 months ago
有问题，就会有答案 - 知乎
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。
Why is $1$ not a prime number? - Mathematics Stack Exchange
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 quickier if 1 is not considered a prime; but I think that group theory was the other force

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