Give the matrix equation below, what is the value of $ab$ ?

$$\begin{bmatrix} 5 & -6 \\ 3 & 12 \end{bmatrix} + \begin{bmatrix} a & 2 \\ 0 & b \end{bmatrix} = \begin{bmatrix} 10 & -4 \\ 3 & 4 \end{bmatrix}$$

Summary Submit Skip Question

Matrix addition invovles addition of corresponding entries.

$$\begin{bmatrix} 5 & -6 \\ 3 & 12 \end{bmatrix} + \begin{bmatrix} a & 2 \\ 0 & b \end{bmatrix} = \begin{bmatrix} 10 & -4 \\ 3 & 4 \end{bmatrix}$$ $$ab = (-5)(-8) = \boxed{-40}$$