Border Matrix in Pluto

General Usage
4

CommonMark seems to work for me instead of the built in Markdown. It works in many situations where Markdown doesn’t work: CommonMark Math in Pluto

I had to remove the comments in the latex since they seemed to break the parser but worked fine after that.

# ╔═╡ d1657bc0-61e4-4129-9dd5-7bd7e89a3629
using CommonMark

# ╔═╡ f23b0978-7f30-47b1-b6bd-dbb72c25b82f
cm"""
``
\begin{align}
  f(x) &= ax^2 + bx + c \\
  &= \begin{array}{c c}
    & \begin{array} {@{} c c c @{}}
      u_1 & \cdots & u_q
    \end{array} \\
    \begin{array}{c}
      e_1 \\ \vdots \\ e_n
    \end{array}\hspace{-1em} &
    \left(
      \begin{array}{@{} c c c @{}}
        u_{11} & \cdots & u_{1q} \\
        \vdots &        & \vdots \\
        u_{n1} & \cdots & u_{nq}
      \end{array}
    \right) \\
    \mbox{} 
  \end{array}
  &= ax^2 + bx + c
\end{align}
``
"""