I answered someone's question, and wanted to use the align environment. For some reason, it's not letting me. The link to the question is below. You can see in my answer that the TeX code is what shows up rather than the actual formatted math. Can anyone help me fix this?
Determine whether each of $V_1$, $V_2$, $V_3$ is a subspace of $\mathbb{R}^4$
\underbrace{1+1}_{= 2}
. $\endgroup$ – Najib Idrissi Mar 14 '15 at 17:24