# Math Help - determinant

1. ## determinant

ahhhh

2. Originally Posted by needhelpsobad
ahhhh
$\left ( \begin{matrix} a & b \\ c & d \end{matrix} \right ) \cdot \left ( \begin{matrix} e & f \\ g & h \end{matrix} \right ) = \left ( \begin{matrix} ae + bg & af + bh \\ ce + dg & cf + dh \end{matrix} \right )$

$\text{det} \left ( \begin{matrix} a & b \\ c & d \end{matrix} \right ) = ad - bc$

-Dan

3. Originally Posted by needhelpsobad
ahhhh
For (c), you can use the equality in (b) to show that AB is singular since det(AB)=0.