Further Maths - Determinants


What is the determinant of a matrix?


A special value associated with a matrix.

What does $ \vert M \vert $ mean in the context of matricies?


The determinant of the matrix $M$.

What does $\text{det} M$ mean?


The determinant of matrix $M$.

What’s the formula for the determinant of a $2x2$ matrix?


\[ad - bc\]

What is $M$ if $\text{det} M$ is $0$?


$M$ is a singular matrix.

What is $M$ if $\text{det} M$ is _ _ not _ _ $0$?


$M$ is a non-singular matrix.

The determinant of a singular matrix is?


$0$.

What is special about singular matricies?


They do not have an inverse.

What is the determinant for
\[\left( \begin{matrix}a & b \\ c & d\end{matrix} \right)\]

?? $ad-bc$

What is the determinant for
\[\left( \begin{matrix}6 & 5 \\ 1 & 2\end{matrix} \right)\]

?? $7$.

What is the determinant for

\[\left( \begin{matrix}a & b \\ c & d\end{matrix} \right)\]

?


$ad-bc$

What is the determinant for

\[\left( \begin{matrix}6 & 5 \\ 1 & 2\end{matrix} \right)\]

?


$7$.

What is the minor of 5 in the matrix
\[\left( \begin{matrix} 1 & 5 & 1 \\ 2 & 0 & 3 \\ 6 & 5 & 4 \end{matrix} \right)\]

??

  • $2 \times 4 - 3 \times 6$
  • $-10$
What is the minor of 7 in the matrix
\[\left( \begin{matrix} 5 & 0 & 2 \\ -1 & 8 & 1 \\ 6 & 7 & 3 \end{matrix} \right)\]

?? $7$.

What is the minor of an element in a matrix?


The determinant of the matrix that remains after the row and column containing that elemnt have been crossed out.

What is the formula for the determinant of
\[\left( \begin{matrix} a & b & c \\ d & e & f \\ g & h & i \end{matrix} \right)\]

??

\[a \times \text{det}\left( \begin{matrix} e & f \\ h & i \end{matrix} \right) - b \times \text{det}\left( \begin{matrix} d & f \\ g & i \end{matrix} \right) + c \times \text{det}\left( \begin{matrix} d & e \\ g & h \end{matrix} \right)\]

What is the process, but not the formula, for finding the determinant of a $3 \times 3$ matrix?


Reduce the $3 \times 3$ matrix to the combined determinants of $3$ $2\times2$ matricies.




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