\documentclass[a4paper,12pt]{article}
\newcommand{\ds}{\displaystyle}
\newcommand{\pl}{\partial}
\parindent=0pt
\begin{document}


{\bf Question}

Find a matrix A with no zero entries such that $A^2 = 0.$

\vspace{.25in}

{\bf Answer}

$\left( \begin{array}{cc}  a & \ds -\frac{a^2}{c} \\ c & -a
\end{array} \right) \hspace{.5in} ac \not= 0$

\end{document}