Hey guys, you can now type LaTeX into discussions and posts (not supported on mobile yet). Just hit the plus button next to the cursor on a new line and choose LaTeX
\left( \sum_{k=1}^n a_k b_k \right)^2 \leq \left( \sum_{k=1}^n a_k^2 \right) \left( \sum_{k=1}^n b_k^2 \right)
We use the KaTeX open source library developed by Khan Academy. You can find sample equations here: KaTeX Demo