Question

(Mack- SP) sabendo que a=|1...3| e b=|1..3..1| calcule a²-2b.
...............................................|2..2|........|2.2..1|
...............................................................|1..1..3|

Answer 1

Olá!

O determinante de A:

$\det(A)=1\cdot2-2\cdot3\\ \det(A)=-4$

O determinante de B (Regra de Sarrus):

$\det(B)=6+3+2-2-1-18\\ \det(B)=-10$

Seja $a=\det(A)$ e $b=\det(B)$, temos que:

$a^2-2b=(-4)^2-2(-10)\\ a^2-2b=16+20\\ a^2-2b=36$

;)