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 …
If $A A^{-1} = I$, does that automatically imply $A^{-1} A = I$?
Mar 30, 2020 · 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 …
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。
Why is $1/i$ equal to $-i$? - Mathematics Stack Exchange
May 11, 2015 · Why is 1/i 1 / i equal to −i i? Ask Question Asked 10 years, 8 months ago Modified 1 year ago Viewed 116k times
为什么美国明明有1小时22分解决委内瑞拉的强大战力，却坐视乌克兰 …
Jan 3, 2026 · 为什么美国明明有1小时22分解决委内瑞拉的强大战力，却坐视乌克兰的巨大牺牲、不愿帮助乌克兰取得胜利？
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?
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。
What does $QAQ^ {-1}$ actually mean? - Mathematics Stack Exchange
Apr 28, 2020 · I'm self-learning Linear Algebra and have been trying to take a geometric approach to understand what matrices mean visually. I've noticed this matrix product pop up repeatedly and can't …
What is the value of $1^i$? - Mathematics Stack Exchange
Aug 30, 2010 · 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 = e …
Word，插入多级列表，但是改了1.1，第二章的2.1也变成1.1，随着改变 …
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 …