Answer
$(a)$. $3B+2C$ is defined and the answer is shown in the image below.
$(b)$. $2H+D$ is undefined.
Work Step by Step
$(a)$. $3B+2C$ is defined because both matrices have the same dimensions $2×3$ . Start by multiplying $3×B$ and $2×C$ then add the products of these matrices as shown in the image below.
$(b)$. $2H+D$,is undefined because we can't add matrices of different dimensions, $2H$ is a $2×2$ matrix and $D$ is a $1×2$ matrix
