## Elementary Linear Algebra 7th Edition

(a) $A+B$ not defined. (b) $A-B$ not defined. (c) \begin{align*} 2A &=\left[\begin{array}{rrr}{12} & {0} & {6} \\ {-2} & {-8} & {0} \end{array}\right]. \end{align*} (d) $2A-B$ not defined. (e) $\frac{1}{2}A+B$ not defined.
Given $$A=\left[\begin{array}{rrr}{6} & {0} & {3} \\ {-1} & {-4} & {0}\end{array}\right], \quad B=\left[\begin{array}{ll}{8} & {-1} \\ {4} & {-3}\end{array}\right]$$ (a) $A+B$ not defined. (b) $A-B$ not defined. (c) \begin{align*} 2A&=2\left[\begin{array}{rrr}{6} & {0} & {3} \\ {-1} & {-4} & {0}\end{array}\right],\\ &=\left[\begin{array}{rrr}{12} & {0} & {6} \\ {-2} & {-8} & {0} \end{array}\right]. \end{align*} (d)$2A-B$ not defined. (e) $\frac{1}{2}A+B$ not defined.