## Linear Algebra: A Modern Introduction

$\begin{bmatrix}3 & -6\\-5 & 7\end{bmatrix}$
We have $A+2D=\begin{bmatrix}3 & 0\\-1 & 5\end{bmatrix}+2\begin{bmatrix}0 & -3\\-2 & 1\end{bmatrix}$ $=\begin{bmatrix}3 & 0\\-1 & 5\end{bmatrix}+\begin{bmatrix} 0 &\ -6\\-4 & 2 \end{bmatrix}$ After matrix addition, we get $=\begin{bmatrix}3 & -6\\-5 & 7\end{bmatrix}$