no. 20. determinan matriks L adalah

[tex]A=\left[ \begin {array}{ccc} a&b&c\\ \noalign{\medskip}d&e&f \\ \noalign{\medskip}g&h&i\end {array} \right] \\ \\ \det(A)=aei-afh-bdi+bfg+cdh-ceg[/tex]

[tex]L=\left[ \begin {array}{ccc} 3&2&1\\ \noalign{\medskip}4&5&2 \\ \noalign{\medskip}0&-1&0\end {array} \right],\qquad \det(L)=2[/tex]