Mathpix (no relation)
Take a photo of
a handwritten math problem
and get
the LaTeX code from your smartphone (or computer)
Take a photo on the iPhone, and crop it.
Submit and voilá.
\begin{equation}
\[
\therefore R_{1}=\left(\frac{q a}{2}\right)\left[2-\alpha^{2}(1+\beta)\right] \end{equation}
\]