Latex infinity symbol

$\infty$
\[\infty\]

Latex interval infinity

$]-\infty, +\infty[$
\[]-\infty, +\infty[\]

Latex limit x to infinity

$\lim_{x \to +\infty} f(x)$
\[\lim_{x \to +\infty} f(x)\]

Latex sum n to infinity

$\sum_{n=1}^{\infty} \frac{1}{n^2}$
\[\sum_{n=1}^{\infty} \frac{1}{n^2}\]