Chapter 2.1, Problem 1E

In Exercises 1 and 2, compute each matrix sum or product if it is defined. If an expression is undefined, explain why. Let

$A=\left[\begin{array}{ccc}2& 0& -1\\ 4& -5& 2\end{array}\right]$, $B=\left[\begin{array}{ccc}7& -5& 1\\ 1& -4& -3\end{array}\right]$,

$C=\left[\begin{array}{cc}1& 2\\ -2& 1\end{array}\right]$, $D=\left[\begin{array}{cc}3& 5\\ -1& 4\end{array}\right]$, $E=\left[\begin{array}{c}-5\\ 3\end{array}\right]$

1. −2A, B−2A, AC, CD