Question

please help

Answer 1

2matrix multiplication , each term in the result is a dot product of the column vector and the row vector...

Answer 2

here is the pattern a couple scrolls down
http://www.mathsisfun.com/algebra/matrix-multiplying.html

Answer 3

i got this answer

Answer 4

by definition of product between matrices, we get this:
\[\begin{gathered}
\left( {\begin{array}{*{20}{c}}
{ - 1}&{ - 2} \\
2&1
\end{array}} \right) \cdot \left( {\begin{array}{*{20}{c}}
3&1 \\
{ - 1}&2
\end{array}} \right) = \hfill \\
\hfill \\
= \left( {\begin{array}{*{20}{c}}
{ - 1 \cdot 3 + \left( { - 2} \right) \cdot \left( { - 1} \right)}&{\left( { - 1} \right) \cdot 1 + \left( { - 2} \right) \cdot 2} \\
{2 \cdot 3 + 1 \cdot \left( { - 1} \right)}&{2 \cdot 1 + 1 \cdot 2}
\end{array}} \right) \hfill \\
\end{gathered} \]