LaTeX
Configuration
This site uses KaTeX for rendering mathematics. The configured delimiters are:
Inline: $...$ or \(...\)
Display: $$...$$ or \[...\]
Additionally, you can use code blocks for block-level formulas:
E = mc^2
For vscode, you might want to ensure your preview settings match these delimiters.
Good memory is not as bad as a pen.
Permutation
$ A_n^n=n\times(n-1)\times(n-2)\times…\times2\times1 $
$ A_n^m=n\times(n-1)\times(n-2)\times…\times(n-m+1) = \frac{n!}{(n-m)!} $
Combination
$ C_n^m=\frac{A_n^m}{A_m^m} = \frac{n!}{m!(n-m)!} $
C_n^m=C_n^{n-m}
$ C_{n+1}^{r+1} = C_n^r + C_n^{r+1} $
Binomial theorem
(a+b)^n = \sum_{i=0}^n{{C_n^i}a^{n-i}b^i} \tag 1
2^n =\sum_{i=0}^n{{C_n^i}} = C_n^0 + C_n^1 + C_n^2 + ... + C_n^n
\begin{equation}
E=mc^2
\end{equation}
$$1 + 1 = 2$$