By clicking on the following formula you find the required formatting to generate that formula.
$ a_1^2 + a_2^2 = a_3^2 $ 

University of Michigan - Ann Arbor

1. A regression model
2. Subscripts and superscripts
3. Fractions and Binomials
4. Integrals
5. Sums
6. Limits

Mathematical formulas in 1Cademy

https://math.meta.stackexchange.com/questions/5020/mathjax-basic-tutorial-and-quick-reference

By clicking on the following formula you find the required formatting to generate that formula.
$y \sim ax_1^2 + bx_2 + c + \epsilon $ 

By clicking on the following formula you find the required formatting to generate that formula.
$$\int_{a}^{b} x^2 dx$$ 

By clicking on the following formula you find the required formatting to generate that formula.
$\frac{P(x)(2n+1)}{6}$ 

By clicking on the following formula you find the required formatting to generate that formula.
$$\sum_{n=1}^{\infty} 2^{-n} = 1$$   

By clicking on the following formula you find the required formatting to generate that formula.
$$\lim_{x\to\infty} f(x)$$ 