Answer
a. $\left[\begin{array}{lll}
8 & 0 & -4\\
14 & 0 & 6\\
-1 & 0 & 0
\end{array}\right]$
b. $\left[\begin{array}{lll}
-4 & -20 & 0\\
14 & 24 & 14\\
9 & -4 & 4
\end{array}\right]$
c. $\left[\begin{array}{lll}
-8 & 40 & 8\\
-56 & -48 & -40\\
-16 & 8 & -8
\end{array}\right]$
d. $ \left[\begin{array}{lll}
18 & -10 & -10\\
42 & 12 & 22\\
2 & -2 & 2
\end{array}\right]$
Work Step by Step
a.
$A+B=[a_{ij}+b_{ij}]$
$=\left[\begin{array}{lll}
2+6 & -10+10 & -2+2\\
14+0 & 12+(-12) & 10+(-14)\\
4+(-5) & -2+2 & 2+(-2)
\end{array}\right]$
$=\left[\begin{array}{lll}
8 & 0 & -4\\
14 & 0 & 6\\
-1 & 0 & 0
\end{array}\right]$
b.
$A-B=[a_{ij}-b_{ij}]$
$=\left[\begin{array}{lll}
2-6 & -10-10 & -2-2\\
14-0 & 12-(-12) & 10-(-14)\\
4-(-5) & -2-2 & 2-(-2)
\end{array}\right]$
$=\left[\begin{array}{lll}
-4 & -20 & 0\\
14 & 24 & 14\\
9 & -4 & 4
\end{array}\right]$
c.
$-4A=\left[-4a_{ij}\right]$
$=\left[\begin{array}{lll}
-8 & 40 & 8\\
-56 & -48 & -40\\
-16 & 8 & -8
\end{array}\right]$
d.
$3A+2B=\left[3a_{ij}+2b_{ij}\right]$
$=\left[\begin{array}{lll}
6+12 & -30+20 & -6-4\\
42+0 & 36-24 & 30-8\\
12-10 & -6+4 & 6-4
\end{array}\right]$
$=\left[\begin{array}{lll}
18 & -10 & -10\\
42 & 12 & 22\\
2 & -2 & 2
\end{array}\right]$
