1. The problem is to multiply the matrix $ \begin{bmatrix} a & b \\ c & d \end{bmatrix} $ by the scalar 3. 2. The formula for scalar multiplication of a matrix is to multiply each element of the matrix by the scalar: $$ 3 \times \begin{bmatrix} a & b \\ c & d \end{bmatrix} = \begin{bmatrix} 3a & 3b \\ 3c & 3d \end{bmatrix} $$ 3. This means each element in the matrix is multiplied by 3 individually. 4. So the resulting matrix after multiplication is: $$ \begin{bmatrix} 3a & 3b \\ 3c & 3d \end{bmatrix} $$ This is the final answer.