There are two ways
In the html editor just type LaTex code between symbols \( … \) (inline).
If you wish to have mathematical symbols in one line per line (display math) just type LaTex code between symbols \[ … \] or $$ … $$
Example:
\[S(f)(t)=a_{0}+\sum_{n=1}^{+\infty}a_n \cos(n \omega t)+b_n \sin(n \omega t)\]
For further examples take a look at:
https://eclass.uoa.gr/modules/exercise/?course=NOC198
In the html editor click on icon 'more' and then click on icon 'source code'.
Use PhpMathPublisher code between tags: [m]…[/m]
Example:
[m]S(f)(t)=a_{0}+sum{n=1}{+infty}{a_{n} cos(n omega t)+b_{n} sin(n omega t)}[/m]
[m]delim{lbrace}{matrix{3}{1}{{3x-5y+z=0} {sqrt{2}x-7y+8z=0} {x-8y+9z=0}}}{ }[/m]
[m]delim{|}{{1/N} sum{n=1}{N}{gamma(u_n)} - 1/{2 pi} int{0}{2 pi}{gamma(t) dt}}{|} <= epsilon/3[/m]
Further Examples:
You can type chemical symbols using MathJax
Type latex code between symbols \( … \)
if you want one line per line type code between \\[ … \\] or \$\$ … \$\$.
Type chemistry symbols using \ce
For further examples take a look at: