Question

Find each product, if possible.

$\left[\begin{array}{cc}2& -1\end{array}\right]\cdot \left[\begin{array}{c}5\\ 4\end{array}\right]$

Short answer

The required matrix is$\left[6\right]$

Step-by-step solution

Step 1- Use the first elements of both matrices

Write the multiplication of first element of first matrix and first element of second matrix to form the first row of product matrix.$[2\cdot 5]$

– Use the second elements of both matrices

Write the multiplication of second element of first matrix and second element of second matrix and add this to previous multiplication to form the complete row of product matrix

$[2\cdot 5+(-1)\cdot 4]$

Step 3- Write the actual product matrix

Perform simplification of obtained matrix.$\left[6\right]$