Question

x x   
5 x = 0

Answer 1

Diagonal principal:
x.x = x²

Diagonal secundária:
5.x = 5x

Det => x² - 5x = 0
Det => x² - 5x - 0

Δ = (5)² - 4.1.0
Δ = 25

x = -(-5) +/- √25 = 5 +/- 5        
           2.1              2
x' = 5 + 5 / 2 = 10 / 2 = 5
x'' = 5 - 5 / 2 = 0 / 2 = 0

Det = x² + 5x

Det' = 5² + 5.5
Det' = 25 + 10
Det' = 35

Det'' = 0