Question

Considere as matrizes A2 = (2 1 1@1 2 1@1 1 2) e I= (1 0 0@0 1 0@0 0 1)
A )Obtenha todos os elementos da Matriz C, tal que C = A2 - 3 . I
B) Calcule o valor do determinante da Matriz C

Answer 1

> C = A2 - 3I

3 0 0
3I = 0 3 0
0 0 3

2 1 1 3 0 0 -1 1 1
C = 1 2 1 - 0 3 0 = 1 -1 1
1 1 2 0 0 3 1 1 -1


C = (- 1 1 1 @ 1 -1 1 @ 1 1 -1) #

detC = (-1 × -1 × -1) + ( 1 × 1 × 1) + (1 × 1 × 1) - [( 1 × -1 × 1) + (1 × 1 × -1) + ( -1 × 1 × 1)]
detC = ( -1 + 1 + 1 ) - ( -1 -1 -1)
detC = 1 - (-3)
detC = 1 + 3

detC = 4 #