How to write LaTeX in Blogger

I just copied this great script from Mathjax. To be fair, I found it here. Now I type equations beautifully (which is not the same as typing beautiful equations).
The simple OLS coefficient estimate:
$$\hat{\beta} = (X'X)^{-1}(X'y)$$
Logit probabilities for a respondent $i$ choosing alternative $j$:
$$P_{ij}=\frac{e^{U_{ij}}}{\sum_k e^{U_{ik}}}$$
and so on ...