Question

calcule o determinante das matrizes
A= 3 2 1
1 5 2
2 1 4

Answer 1

$\boxed{\begin{array}{l}\sf A=\begin{vmatrix}\sf3&\sf2&\sf1\\\sf1&\sf5&\sf2\\\sf2&\sf1&\sf4\end{vmatrix}\\\sf det~A=3(20-2)-2(4-4)+1(1-10)\\\sf det~A=54-0-9\\\sf det~A=45\end{array}}$