Answer
$a.\quad\left[\begin{array}{rrr}
-1 & -3 & -5\\
-1 & 3 & -6
\end{array}\right]$
$b.\quad\left[\begin{array}{rrr}
-14 & -8 & -30\\
-6 & 10 & -24
\end{array}\right]$
Work Step by Step
C and B have the same dimension, so both (a) and (b) are defined.
(a)
$C-B=\left[\begin{array}{lll}
2-3 & -\frac{5}{2}-\frac{1}{2} & 0-5\\
0-1 & 2-(-1) & -3-3
\end{array}\right]=\left[\begin{array}{lll}
-1 & -3 & -5\\
-1 & 3 & -6
\end{array}\right]$
(b)
$2C-6B=\left[\begin{array}{lll}
2(2)-6(3) & 2(-\frac{5}{2})-6(\frac{1}{2}) & 2(0)-6(5)\\
2(0)-6(1) & 2(2)-6(-1) & 2(-3)-6(3)
\end{array}\right]$
$=\left[\begin{array}{lll}
-14 & -8 & -30\\
-6 & 10 & -24
\end{array}\right]$
