Given :
[tex]\begin{gathered} A=\begin{bmatrix}1 & {2} & {} \\ {3} & {4} & \end{bmatrix} \\ B=\begin{bmatrix}{6} & {7} & {} \\ {5} & {8} & \end{bmatrix} \end{gathered}[/tex]
So,
[tex]AB=\begin{bmatrix}{1} & {2} & {} \\ {3} & {4} & {}\end{bmatrix}\begin{bmatrix}{6} & {7} \\ {5} & {8}\end{bmatrix}=\begin{bmatrix}{c11} & {c12} \\ {c21} & {c22}\end{bmatrix}[/tex]
c11 = row 1 column 1 = 1 * 6 + 2 * 5 = 6 + 10 = 16
c12= row 1 column 2 = 1 * 7 + 2 * 8 = 7 + 16 = 23
c21 = row 2 column 1 = 3 * 6 + 4 * 5 = 18 + 20 = 38
c22 = row 2 column 2 = 3 * 7 + 4 * 8 = 21 + 32 = 53
