Question

If $A=⟮\begin{array}{cc}2& 3\\ -9& 5\end{array}⟯-⟮\begin{array}{cc}1& 5\\ 7& -1\end{array}⟯$ , then find the additive inverse of $A$. [3 marks]

Answer 1

$A=⟮\begin{array}{cc}2& 3\\ -9& 5\end{array}⟯-⟮\begin{array}{cc}1& 5\\ 7& -1\end{array}⟯=⟮\begin{array}{cc}2-1& 3-5\\ -9-7& 5+1\end{array}⟯=⟮\begin{array}{cc}1& -2\\ -16& 6\end{array}⟯$
$\left[1.5marks\right]$

$\therefore$ Additive inverse of $A=-A=⟮\begin{array}{cc}-1& 2\\ 16& -6\end{array}⟯$$\left[1.5marks\right]$