Just write $<formula>$ and run org-latex-preview
and it will render it.$RMSE = \sqrt{MSE} = \sqrt{\frac{1}{|D|} \sum_{d \in D} (f(d) - h(d))^2}$ → $RMSE = \sqrt{MSE} = \sqrt{\frac{1}{|D|} \sum_{d \in D} (f(d) - h(d))^2}$
Note that this will be rendered in a ltximg directory, which you might want to add to .gitignore if you're version controlling it.