This is a guide for those who want to learn use $\LaTeX$ or simple formatting. If you want to contribute on brilliant, then you should use $\LaTeX$ in many cases. This makes your posts more readable.

When you don't know how to write a symbol, then use the Google. I will post there only the important symbols.

There are lots of $\LaTeX$ guides, but I think my guide is the most readale and complete. Let's start the learning.

Content:

1. What is Latex

$\LaTeX$ is a formatting(or markdown) language to format documents or write formulas. In this web page we can't format documents, therefore lots of commands isn't working.

2. Basic formatting

This paragraph will help you to format your posts without $\LaTeX$. This is a markdown language, like HTML.

What you type	What you get
*italics* or _italics_	italics
**bold** or __bold__	bold

You can combine the two styles like these:

• ***Hello!***
• *__Hello!__*
• ___Hello!___

All possible combinations are correct. Each will appear as Hello!.

$\\[-20px]$

See this example:

I
love
to
do
it

I love to do this

Now try it with two or more spaces at the end of the lines:

I  
love  
to  
do  
it

I
love
to
do
this

Now try to take empty spaces:

I

love


to



do




it

I

love

to

do

this

If you fil the empty lines with spaces you will get the same result. If you want to take more empty sapces you should use $\LaTeX$ codes. But this isn't the $\LaTeX$ section, so let's continue.

$\\[-20px]$

> It will appear like this quote

It will appear like this quote

Let's see some examples:

> This
is
an
example

This is an example

Now try it with two or more spaces at the end of each lines:

> This  
is  
an  
example

This
is
an
example

Now try to connect two quotes:

> This is


> an example

This is
an example

If you want to separate them, then you should write something between them(this can be an empty $\LaTeX$ code too):

> This is

an

> example

This is

an

example

$\\[-20px]$

- buletted or * bulleted or + bulleted and 1. numbered

Usefull things:

• You always should take an empty line before and after the list(If you don't take before it, then it will appear like a simple text, but if you don't take after it, then the simple text will be

connected to the list) - You should take a space after the - sign

I will show the examples with only bulleted lists:

This isn't a
- bulleted list

- bulleted list  

- bulleted list  
continue

 - shifted list

This isn't a - bulleted list

• bulleted list

• bulleted list
  continue

  • shifted list

$\\$

Let's see this one:

* It

 won't

* break

• It

  won't

• break $\\$

If you should write a date:

1956. Doesn't work  
1956\. Yeah

1. Doesn't work
   1956. Yeah

$\\$

$\\[-20px]$

[<link text>](<link>)

Link text will appear.

[I'm happy](https://translate.google.com/?hl=hu#view=home&%3Bop=translate&%3Bsl=en&%3Btl=hu&%3Btext=I'm%20happy.&op=translate&sl=en&tl=hu&text=I'm%20happy)

I'm happy

There is the empty link

[I'm empty](#)

I'm empty

If you should use a link many times you can define links:

[link][id1]

[id1]: https://brilliant.org/discussions/thread/math-prove-marathon/  "Title"

link

You can use links in $\LaTeX$ too, but this is unnecessary.

$\\[-20px]$

When you upload a picture, then you will get a code. You should only insert it, if you placed to the wrong place(or if you want to insert it to the comment section). But when you want to use a

picture from the internet, then you should only copy the link of the picture: ![text under the picture](<link or uploaded link>){: .<position>}

The position can be: left,center,right. If you delete the {} brackets, then it will be left aligned.

Let's see an example for the three positions and how to combine links and pictures:

![](https://www.shutterstock.com/blog/wp-content/uploads/sites/5/2019/07/Man-Silhouette.jpg){: .left}
[![](https://www.shutterstock.com/blog/wp-content/uploads/sites/5/2019/07/Man-Silhouette.jpg){: .center}](https://d.newsweek.com/en/full/520858/supermoon-moon-smartphone-photo-picture.jpg)
Click to the picture!
![](https://www.shutterstock.com/blog/wp-content/uploads/sites/5/2019/07/Man-Silhouette.jpg){: .right}

Click to the picture!

As you can see if the picture isn't center aligned, then the text after the picture's link will appear next to the picture.

The code of the gif files are the same.

You can give a title to your picture. It won't appear: ![<text under the picture>](<link> "<Title>"){: .<position>}. You can define links to pictures too.

$\\[-20px]$

When we are talking about commands, then we use these:

`readln()`

readln()

We can take lots of ` before it, but then we should take the same amount of this signs after it.

If we want line breaks without break the code block:

```python
print "This is the best sentence"
```

1	print "This is the best sentence"

Sometimes the text after the code block doesn't appear. You should only place a title after the code and it will be good.

If you don't give the name of the programming language:

1	print "This is the best sentence"

You should take an empty line before it. If the text after the code block doesn't appear, then take a # after the block.

$\\[-20px]$

$\\$

If you take 4 spaces, then
it will appear like you typed

similar to the quote
          this will be if you take more than 4 spaces

$\\[-20px]$

$\\$

||1||2||3||
||4||wide column||
||||||same||

||other||table||:)||
||longer||row||than||the first||

1	2	3
4	wide column
		same

other	table	:)
longer	row	than	the first

$\\[-20px]$

We can create 6 different titles(we can close them, but this is unnecessary):

# I'm your ego
## This is sometimes underlined ##
### I'm your IQ
#### Interesting
##### Nothing #####
###### Thin-king

I'm your ego

This is sometimes underlined

I'm your IQ

Interesting

Nothing

Thin-king

$\\[-20px]$

_ =Shift and `-` If under a text we take a - or = these will make a title. If we take an empty line, then these won't:

_

title 1
=

title 2
-

--
* * *
*
- -

---

title 1

title 2

---

---

---

---

$\\[-20px]$

@<name> When you start the typing to mention somebody, then the web page will give you options. If you don't choose one, then it won't work. You should choose the correct option. If the web page don't give you the required name, then continue the typing or try to type the name another way(for example without space).

$\\[-20px]$

Idea from Percy Jackson

[[show-hide-button|<Button text>]]   
[[start-hidden]]   
<Content> 
[[end-hidden]]

You can use buttons only in notes, but you can't use nested buttons.

3. Basic latex operators and modificators

The interpreter should distinct the $\LaTeX$ codes, so we should mark them. We can mark two types of $\LaTeX$ placement:

• \$$(<code>\)
• \$$[<code>\]

The first type of $\LaTeX$ placement will appear like this $1+2=3$, but the second will like this $1+2=3$. Both codes are placed into the sentence, but the second makes a break line before and after itself and the second is center aligned.

$\\[-20px]$

Spaces sometimes are allowed, sometimes they are necessary but sometimes they are unallowed. Let's see the rules:

Rule	Example code	How will ppear
Between the brackets the spaces are unallowed	\ ( 1+3\ )	\ ( 1+3\ )
In a command the spaces don't allowed	\$$(\ta n(x)\)	$\ta n(x)$
After a command if the next character is a letter, then the space is necessary	\$$(\tanx\)	$\tanx$
In other cases the spaces are allowed	\$$(3$\;\;$+$\;\;$4 = 7\)	$3 + 4 = 7$
Line breaks are allowed when spaces are allowed	\$$(1 + $\\$ 3 = 4\)	$1 + 3 = 4$

But these spaces won't appear. There you can see how to take a space:

Code	Appearance	Note
\,	$te\,xt$
\:	$te\:xt$
\;	$te\;xt$
\!	$te\!xt$	If you take more\!: $te\!\!\!\!xt$
~	$te~xt$

Or you can insert a text or outside the brackets you can take one space. With these $\LaTeX$ codes you can take longer spaces.

You can make special spaces:

|{\kern 1pt} |{\kern 10pt} |{\kern 100pt}|\\
|\hspace{1pt} |\hspace{10pt} |\hspace{100pt}|

$|{\kern 1pt} |{\kern 10pt} |{\kern 100pt}|\\ |\hspace{1pt} |\hspace{10pt} |\hspace{100pt}|$

$pt$ is a given length like $cm$ and $mm$. In$\LaTeX$ (and in web building) there are other units, but the main units are: $\text{pt, px, em}$

Let's see how to make line breakes with special length:

4\\[30px]5

$4\\[30px]5$

You can give not integer numbers and negative numbers also.

54
5\hspace{0.7px}4
5\hspace{-4px}4

$54$
$5\hspace{0.7px}4$
$5\hspace{-4px}4$

$0.7=.7$

Here is some information about other length:

$\rule{5in}{10px}$ 5 in
$\rule{5cm}{10px}$ 5 cm
$\rule{5cc}{10px}$ 5 cc
$\rule{5nc}{10px}$ 5 nc
$\rule{5pc}{10px}$ 5 pc
$\rule{5em}{10px}$ 5 em
$\rule{5ex}{10px}$ 5 ex
$\rule{5mm}{10px}$ 5 mm
$\rule{5dd}{10px}$ 5 dd
$\rule{5nd}{10px}$ 5 nd
$\rule{5px}{10px}$ 5 px
$\rule{5bp}{10px}$ 5 bp
$\rule{5pt}{10px}$ 5 pt
$\rule{5sp}{10px}$ 5 sp

$\\[-20px]$

What you type	What you get	Note
2=2	$2=2$
1+2	$1+2$
4*6	$4*6$	If you use other commands, then it will appear better
4\times6	$4\times6$	If you are on mobile, then maybe you can find it at the symbols
4\cdot6	$4\cdot6$
8/4	$8/4$	you can use other commands too
8\div4	$8\div4$	On mobile you can write it without code
\frac{8}{4}	$\frac{8}{4}$	You can use modificators. \frac 123 will be $\frac 123$
{3\choose2}	${3\choose2}$
\binom{3}{2}	$\binom{3}{2}$
2^3	$2^3$	If you want to write $2^{33}$, than you should write 2^{33}, without the { and } brackets it will appear like this $2^33$
2^{3^3}	$2^{3^3}$	If you don't write brackets: 2^3^3
A_1	$A_1$	Same way as ^ if you want to write more characters you should use { and } brackets
A_{1_2}	$A_{1_2}$
\sqrt{3}	$\sqrt{3}$
\sqrt[4]{5}	$\sqrt[4]{5}$
\parallel	$\parallel$
\perp	$\perp$

After the basic operators let's see some often used commands. There are some built in functions like \tan, \log, \gcd, \mod.... We can avoid them, but using them is easier. Let's see an

example: \tan(x)=1 and tan(x) will appear like $\tan(x)$ and $tan(x)$.

$\\[-20px]$

\left ( \right )	$\left ( \right )$
\left \| \right \|	$\left \| \right \|$
\left [ \right ]	$\left [ \right ]$
\left \langle \right \rangle	$\left \langle \right \rangle$
\left \{ \right \}	$\left \{ \right \}$
\left \lfloor \right \rfloor	$\left \lfloor \right \rfloor$
\left | \right |	$\left | \right |$
\left \lceil \right \rceil	$\left \lceil \right \rceil$

$\\[-20px]$

Sometimes we should use modificators. Let's see an example: $\frac{\frac{2}{\frac{5}{6}+7}+3}{4^8}$. As you can see this is too small. The modificators help us to set the size of the operators.

If we use the \displaystyle modificator before each fraction, then it will set the size automatically:

\displaystyle\frac{\displaystyle\frac{2}{\displaystyle\frac{5}{6}+7}+3}{4^8}

$\displaystyle\frac{\displaystyle\frac{2}{\displaystyle\frac{5}{6}+7}+3}{4^8}$

This is a long way to solve this problem, so we can use \dfrac{}{}. We will get the same result. With fractions there are some more modificators. Let's see all of them in one table:

Code	Appearance
\frac{2+\frac{1}{5}}{\frac{7}{6}+4}	$\frac{2+\frac{1}{5}}{\frac{7}{6}+4}$
\displaystyle\frac{2+\displaystyle\frac{1}{5}}{\displaystyle\frac{7}{6}+4}	$\displaystyle\frac{2+\displaystyle\frac{1}{5}}{\displaystyle\frac{7}{6}+4}$
\dfrac{2+\dfrac{1}{5}}{\dfrac{7}{6}+4}	$\dfrac{2+\dfrac{1}{5}}{\dfrac{7}{6}+4}$
\cfrac{2+\cfrac{1}{5}}{\cfrac{7}{6}+4}	$\cfrac{2+\cfrac{1}{5}}{\cfrac{7}{6}+4}$
\tfrac{2+\tfrac{1}{5}}{\tfrac{7}{6}+4}	$\tfrac{2+\tfrac{1}{5}}{\tfrac{7}{6}+4}$

Here is two examples with $\!\!\!\!\mod\!$:

Code	Appearance
2\mod4	$2\mod4$
2\bmod4	$2\bmod4$
2\pmod4	$2\pmod4$

The \displaystyle won't do anything.

In some cases the \displaystyle works only. Let's see some examples(I wrote the modificators before the operators):

Original	Modificated
$2^{3^{4^{5^6}}}$	$2\displaystyle^{3\displaystyle^{4\displaystyle^{5\displaystyle^6}}}$
$A_{B_{C_{D_E}}}$	$A\displaystyle_{B\displaystyle_{C\displaystyle_{D\displaystyle_E}}}$
$\sum_a^b$	$\displaystyle\sum_a^b$

Sometimes modificators cause some problem:

$(\dfrac{\dfrac{4}{6}+2}{1})$

You can try the \displaystyle won't help. When we use brackets we use the \left and the \right modificators:

\left ( \dfrac{\dfrac{4}{6}+2}{1} \right )

$\left ( \dfrac{\dfrac{4}{6}+2}{1} \right )$

But sometimes we use only one bracket(usually when we are working with a matrix). Let's see an example:

\left | \dfrac{\dfrac{4}{6}+2}{1}

\left | \dfrac{\dfrac{4}{6}+2}{1}

As you can see it's not working perfectly. When we start a bracket with a modificator then we should mark the pair of it and same way we can't end a bracket if we didn't marked the pair of it. The solution is easy:

\left | \dfrac{\dfrac{4}{6}+2}{1} \right.

$\left | \dfrac{\dfrac{4}{6}+2}{1}\right.$

$\\[-20px]$

You can make left and center aligned equations already. But sometimes we make lots of modifications on only one side of the equation. Let's see that:

\begin{align}
A&=(4x+5)^2-8\\
&=16x^2+40x+25-8\\
&=16x^2+40x+17
\end{align}

$\begin{aligned} A&=(4x+5)^2-8\\ &=16x^2+40x+25-8\\ &=16x^2+40x+17 \end{aligned}$

& means that where will the lines aligned. So the next characters after the & signs will make a straight vertical line. The \ signs means the line break. We should not take a line break after these signs, when we write the code, but if we take we can modificate easier it. We can use align* too, but it doesn't make anything. Let's see an interesting example:

\begin{align}
1&=333&=333&=22&=22&333&=22&=1\\
1&=22&22&=333&=22&1&=1&=22&=5&=1\\
4444&=1&=1&=1&=333&333&=4444&=1&=22&=55555\\
&&&&4444\\
22
\end{align}

$\begin{aligned} 1&=333&=333&=22&=22&333&=22&=1\\ 1&=22&22&=333&=22&1&=1&=22&=5&=1\\ 4444&=1&=1&=1&=333&333&=4444&=1&=22&=55555\\ &&&&4444\\ 22 \end{aligned}$

• Only each second & will be aligned into a line
• We can skip lines with more & signs
• Not only the = can make a straight line

$\\[-20px]$

Only the often used special characters:

\rightarrow	$\rightarrow$	\Rightarrow	$\Rightarrow$
\leftarrow	$\leftarrow$	\Leftarrow	$\Leftarrow$
\uparrow	$\uparrow$	\Uparrow	$\Uparrow$
\downarrow	$\downarrow$	\Downarrow	$\Downarrow$
\pm	$\pm$	\mp	$\mp$
\leq	$\leq$	\geq	$\geq$
\lfloor	$\lfloor$	\rfloor	$\rfloor$
\lceil	$\lceil$	\rceil	$\rceil$
\therefore	$\therefore$	\because	$\because$
\angle	$\angle$	\triangle	$\triangle$
\equiv	$\equiv$	\approx	$\approx$
\in	$\in$	\ni	$\ni$
\ll	$\ll$	\gg	$\gg$
\neq	$\neq$
|x|,|=AltGr+W	$|x|$
\infty	$\infty$

As you can see there are modifications of the arrows. If you start with a big letter you will get a double arrow. You can use modificators too: long, leftright, updown

There are lots of characters. I won't write all of them. Here you can see more characters.

Let's see the big operators:

\int	$\int$
\iint	$\iint$
\oint	$\oint$
\sum	$\sum$
\prod	$\prod$
\bigcap	$\bigcap$
\bigcup	$\bigcup$

$\\[-20px]$

\Alpha and \alpha	$\Alpha$ and $\alpha$	\Nu and \nu	$\Nu$ and $\nu$
\Beta and \beta	$\Beta$ and $\beta$	\Xi and \xi	$\Xi$ and $\xi$
\Gamma and \gamma	$\Gamma$ and $\gamma$	\Omicron and \omicron	$\Omicron$ and $\omicron$
\Delta and \delta	$\Delta$ and $\delta$	\Pi, \pi and \varpi	$\Pi$, $\pi$ and $\varpi$
\Epsilon, \epsilonand \varepsilon	$\Epsilon$, $\epsilon$ and $\varepsilon$	\Rho, \rho and \varrho	$\Rho$, $\rho$ and $\varrho$
\Zeta and \zeta	$\Zeta$ and $\zeta$	\Sigma, \sigma and \varsigma	$\Sigma$, $\sigma$ and $\varsigma$
\Eta and \eta	$\Eta$ and $\eta$	\Tau and \tau	$\Tau$ and $\tau$
\Theta, \theta and \vartheta	$\Theta$, $\theta$ and $\vartheta$	\Upsilon and \upsilon	$\Upsilon$ and $\upsilon$
\Iota and \iota	$\Iota$ and $\iota$	\Phi, \phi and \varphi	$\Phi$, $\phi$ and $\varphi$
\Kappa, \kappa and \varkappa	$\Kappa$, $\kappa$ and $\varkappa$	\Chi and \chi	$\Chi$ and $\chi$
\Lambda and \lambda	$\Lambda$ and $\lambda$	\Psi and \psi	$\Psi$ and $\psi$
\Mu and \mu	$\Mu$ and $\mu$	\Omega and \omega	$\Omega$ and $\omega$

$\\[-20px]$

{}'	${a}'$
{}''	${a}''$
\dot{}	$\dot{a}$
\ddot{}	$\ddot{a}$
\hat{}	$\hat{a}$
\check{}	$\check{a}$
\grave{}	$\grave{a}$
\acute{}	$\acute{a}$
\tilde{}	$\tilde{a}$
\breve{}	$\breve{a}$
\bar{}	$\bar{a}$
\vec{}	$\vec{a}$
\not{}	$\not{a}$
^{\circ}	$a^{\circ}$

\widetilde{}	$\widetilde{abc}$
\widehat{}	$\widehat{abc}$
\overleftarrow{}	$\overleftarrow{abc}$
\overrightarrow{}	$\overrightarrow{abc}$
\overline{}	$\overline{abc}$
\underline{}	$\underline{abc}$
\overbrace{}	$\overbrace{abc}$
\underbrace{}	$\underbrace{abc}$
\overset{}{}	$\overset{123}{abc}$
\underset{}{}	$\underset{123}{abc}$
\xrightarrow[]{}	$\xrightarrow[123]{abc}$
\xleftarrow[]{}	$\xleftarrow[123]{abc}$

In every case the first brackets contain the 123. You can see we can't use overset and underset at the same time. Instead we can use arrays and matrices. The brackets can contain arrows also: $\overset{\Delta t}{\rightarrow}$

And there is one interesting thing:

\boxed{12.5}=\fbox{12.5}

$\boxed{12.5}=\fbox{12.5}$

And we can do this:

\cancel{123456789}

$\cancel{123456789}$

$\\[-20px]$

\text{} between the brackets everything will appear.

\text{I'm happy...}

$\text{I'm happy...}$

4. Formatting with Latex

Code	Appearance	Code	Appearance
\textnormal{}	$\textnormal{BIG small}$	\mathnormal{}	$\mathnormal{BIG small}$
\textup{}	$\textup{BIG small}$	\boldsymbol{}	$\boldsymbol{BIG small}$	Note: with this code we can print bold symbols: $\boldsymbol{\uparrow}$
\textbf{}	$\textbf{BIG small}$	\mathbf{}	$\mathbf{BIG small}$
\textit{}	$\textit{BIG small}$	\mathit{}	$\mathit{BIG small}$
\textrm{}	$\textrm{BIG small}$	\mathrm{}	$\mathrm{BIG small}$
\textsf{}	$\textsf{BIG small}$	\mathsf{}	$\mathsf{BIG small}$
\textrm{}	$\textrm{BIG small}$	\mathrm{}	$\mathrm{BIG small}$
\texttt{}	$\texttt{BIG small}$	\mathbb{}	$\mathbb{BIG small}$
\textmd{}	$\textmd{BIG small}$
		\mathcal{}	$\mathcal{BIG small}$
		\mathfrak{}	$\mathfrak{BIG small}$

These are unnecessary codes, you shouldn't learn them. As you can see only the text formats will display the spaces.

$\\[-20px]$

\tiny	$\tiny\text{tiny}$
\scriptsize	$\scriptsize\text{scriptsize}$
\footnotesize	$\footnotesize\text{footnotesize}$
\small	$\small\text{small}$
\normalsize	$\normalsize\text{normalsize}$
\large	$\large\text{large}$
\Large	$\Large\text{Large}$
\LARGE	$\LARGE\text{LARGE}$
\huge	$\huge\text{huge}$
\Huge	$\Huge\text{Huge}$

If we place the code in a title:

$\Huge \text{Bubu}$

$\Huge \text{Bubu}$

$\\[-20px]$

There are built in colores:

\red{}, \blue{}, \green{}, \orange{} etc.

$\red{red rat}$

We can use \color{}. Between the brackets we should give the name of the color. This will be active until you don't change the color again.

There are two ways to give the color:

• \color{red}, \color{blue}, \color{black}
• With hexadecimal code: \color{#<code>}

Let's see an example to the second: If our color is the basic red, then with RGB($\color{#ff0000}\text{Red}\color{#00ff00}\text{Green}\color{#0000ff}\text{Blue}$)

coloring:

$\color{#ff0000}\text{Red}=100\%$	$100\%=(256)_{10}$	$(256)_{10}=(FF)_{16}$
$\color{#00ff00}\text{Green}=0\%$	$0\%=(0)_{10}$	$(0)_{10}=(00)_{16}$
$\color{#0000ff}\text{Blue}=0\%$	$0\%=(0)_{10}$	$(0)_{10}=(00)_{16}$

So the code will be \color{#FF0000}: $\color{#ff0000}\text{red}$

Let's see a complex color: #4DA3EC $\color{#4da3ec} color$

Here you can set the color and get the code of it.

If we use the color command between two { } brackets, then the text after the brackets won't be colored:

{\color{green}green}black

${\color{#20A900}green}black$

Let's see an interesting example:

\color{red}red{\color{green}green}unknown

$\color{#D61F06}red{\color{#20A900}green}unknown$

We can use \textcolor{} also:

\textcolor{red}{red}

$\textcolor{#D61F06}{red}$

\textcolor{red}red

$\textcolor{#D61F06}red$

But we can make color boxes:

\colorbox{blue}{black\color{#FFFFFF}white}

$\colorbox{#3D99F6}{black\color{#ffffff}white}$

And we can make color boxes with border:

\fcolorbox{red}{blue}{\text{The text command include the whole text, but the brackets are necessary}}

$\fcolorbox{#D61F06}{#3D99F6}{\text{The text command include the whole text, but the brackets are necessary}}$

5. Matrices and arrays

Matrices are similar to tables and to the aligned equations. & means the next column an \ means the next row(If \ is annoying, then you can use \cr):

\begin{matrix}
1 & 2 & 3\\
4 & 5 & 6
\end{matrix}

$\begin{matrix} 1 & 2 & 3\\ 4 & 5 & 6 \end{matrix}$

Like with tables, there you can skip columns and you can make longer rows than the first:

\begin{matrix}
1 & 2 & 3\\
1 & 2 &
3 & 4 & 5\\
&&3&&5
\end{matrix}

$\begin{matrix} 1 & 2 & 3\\ 1 & 2 & 3 & 4 & 5\\ &&3&&5 \end{matrix}$

You can see if we won't write a whole line we can skip the & symbols. And you can see also that I taked a line break, but it doesn't displayed.

Let's see the types of the matrices:

• pmatrix

---

\begin{pmatrix}
1 & 2 & 3\\
4 & 5 & 6
\end{pmatrix}

$\begin{pmatrix} 1 & 2 & 3\\ 4 & 5 & 6 \end{pmatrix}$

• bmatrix

---

\begin{bmatrix}
1 & 2 & 3\\
4 & 5 & 6
\end{bmatrix}

$\begin{bmatrix} 1 & 2 & 3\\ 4 & 5 & 6 \end{bmatrix}$

• Bmatrix

---

\begin{Bmatrix}
1 & 2 & 3\\
4 & 5 & 6
\end{Bmatrix}

$\begin{pmatrix} 1 & 2 & 3\\ 4 & 5 & 6 \end{pmatrix}$

• vmatrix

---

\begin{vmatrix}
1 & 2 & 3\\
4 & 5 & 6
\end{vmatrix}

$\begin{vmatrix} 1 & 2 & 3\\ 4 & 5 & 6 \end{vmatrix}$

• Vmatrix

---

\begin{Vmatrix}
1 & 2 & 3\\
4 & 5 & 6
\end{Vmatrix}

$\begin{Vmatrix} 1 & 2 & 3\\ 4 & 5 & 6 \end{Vmatrix}$

But we can use special matrices too:

\left\{\left. \begin{matrix}
1 & 3 & 5\\
7 & 4 & 9
\end{matrix}\right |\right.

$\left\{\left. \begin{matrix} 1 & 3 & 5\\ 7 & 4 & 9 \end{matrix}\right |\right.$

But we can place a matrix into another matrix:

\begin{matrix}
1 & \begin{matrix}
2 & 3\\ 
4 & 5
\end{matrix}\\ 
6 & 7
\end{matrix}

$\begin{matrix} 1 & \begin{matrix} 2 & 3\\ 4 & 5 \end{matrix}\\ 6 & 7 \end{matrix}$

We can insert horizontal lines into the matrix with \hline:

\begin{matrix}
2 & 4\\
\hline 5 & 6
\end{matrix}

$\begin{matrix} 2 & 4\\ \hline 5 & 6 \end{matrix}$

If we need a vertical line, then we should use two matrices or use an array. Let's see the arrays.

$\\[-20px]$

The arrays are similar to matrices, but when we begin an array, then we should give the align of each colummn:

\begin{array}{<align>}
<array>
\end{array}

<align> can be:

• c - center
• l - left
• r - right

If we have more columns than that we have declared we will get an error message. But we can skip the empty columns. Let's see an example:

\begin{array}{lcr}
7777777 & 4444 & 666666\\
4444 & 1\\
22&&999999999
\end{array}

$\begin{array}{lcr} 7777777 & 4444 & 666666\\ 4444 & 1\\ 22&&999999999 \end{array}$

Now let's see how to insert a vertical line:

\begin{array}{c|c}
1 & 2\\
3 & 4\\
5 & 6\\
\end{array}

$\begin{array}{c|c} 1 & 2\\ 3 & 4\\ 5 & 6\\ \end{array}$

$\\[-20px]$

\begin{cases}
y=1 & x=5  \\ 
y=2 & x=4 \\ 
y=3 & x=3 \\ 
y=4 & x=2 \\ 
y=5 & x=1 
\end{cases}

$\begin{cases} y=1 & x=5 \\ y=2 & x=4 \\ y=3 & x=3 \\ y=4 & x=2 \\ y=5 & x=1 \end{cases}$ You can't add new columns. But if you insert a matrix, then you can solve it.

$\\[-20px]$

There are lots of dots. Here you can see the main codes(from wikibooks):

\dots	$\dots$	Generic dots (ellipsis), to be used in text (outside formulae as well). It automatically manages whitespaces before and after itself according to the context, it's a higher level command.
\ldots	$\ldots$	The output is similar to the previous one, but there is no automatic whitespace management; it works at a lower level.
\cdots	$\cdots$	These dots are centered relative to the height of a letter. There is also the binary multiplication operator, \cdot, mentioned below.
\vdots	$\vdots$	vertical dots
\ddots	$\ddots$	diagonal dots

6. Not math codes

This web page doesn't support all $\LaTeX$ codes. Therefore we can't use lots of not mathematical codes. I think only basic formatting, chemical equations and square drawing are supported. Let's see the chemical equations:

You can already write chemical equations:

\text{CH}_4+2\text{O}_2\rightarrow2\text{H}_2\text{O}+\text{CO}_2

$\text{CH}_4+2\text{O}_2\rightarrow2\text{H}_2\text{O}+\text{CO}_2$

But this can be easier:

\ce{CH4 + 2O2 -> 2H2O + CO2}

$\ce{CH4 + 2O2 -> 2H2O + CO2}$

Here you can see the main things(these are the examples from there):

\ce{H2O}	$\ce{H2O}$
\ce{CrO4^2-}	$\ce{CrO4^2-}$
\ce{A <--> B}	$\ce{A <--> B}$
\ce{A ->[x_i] B}	$\ce{A ->[x_i] B}$
\ce{CO2 + C -> 2 CO}	$\ce{CO2 + C -> 2 CO}$
\ce{A\bond{~--}B\bond{~=}C\bond{-~-}D}	$\ce{A\bond{~--}B\bond{~=}C\bond{-~-}D}$

Spaces are necessary

And the square drawing:

\rule[raise]{width}{height}

\rule{78pt}{.4cm}\color{red}\rule[.2cm]{24px}{2 mm}\hspace{-24px}\color{blue}\rule{24px}{2mm}

$\rule{78pt}{.4cm}\color{#D61F06}\rule[.2cm]{24px}{2 mm}\hspace{-24px}\color{#3D99F6}\rule{24px}{2mm}$

For more information see: 3.2. Spaces and line breaks

7. Useful tips

• Don't write a lot of text in $\LaTeX$. This can be annoying, and in small screens others can't read your text
• Make your code always readable. If you have an error, then you can edit it quickly
• If you can't follow your brackets, then take line breaks or spaces
• Remember to check the spaces after each codes
• Always check the end of the $\LaTeX$ code. If your code doesn't end, your will face many errors.
• Use readable font size, but not too big (\LARGE is usually too big).
• Use the Preview button before you post something. The $\LaTeX$ sometimes doesn't displayed. Use any online editor to see your codes
• If you have written a lot of code, then save it, as the web page doesn't always save your codes.
• $\color{#D61F06}\text{Don't take big line breaks. You can take 500000px long line breaks, but don't do that!}$
• Don't copy codes from others

8. Tasks

You can make symbols with negative spaces, rectangles, characters.... There are two examples from my note about programming tasks:

$\color{#888888}\Large\bigodot \hspace{-666200sp}\rule[3px]{1.3px}{5.5px}\hspace{-289000sp}\rule[11.5px]{7.5px}{1.7px}$ $\hspace{1pt}$

$\color{#888888}\rule[4px]{14px}{2.2px}\hspace{-14px}\rule{14px}{2.2px}\hspace{-14px}\rule[-4px]{14px}{2.2px}$

Make a special symbol and I will include it

And the big question:

• The big question: How to write $\LaTeX$
• Answer: \LaTeX

Here is a cool website, where you can make equations without learning codes.