Série 2 : exo 2

[ 1, -2, -1,  3, 0]
[-2,  4,  5, -5, 3]
[ 3, -6, -6,  8, 2]

L_2 <- L_2 + 2 * L_1

[1, -2, -1, 3, 0]
[0,  0,  3, 1, 3]
[3, -6, -6, 8, 2]

L_3 <- L_3 - 3 * L_1

[1, -2, -1,  3, 0]
[0,  0,  3,  1, 3]
[0,  0, -3, -1, 2]

L_3 <- L_3 + 1 * L_2

[1, -2, -1, 3, 0]
[0,  0,  3, 1, 3]
[0,  0,  0, 0, 5]

L_3 <- 1/3 * L_3

[1, -2, -1, 3,   0]
[0,  0,  3, 1,   3]
[0,  0,  0, 0, 5/3]

Le système n'est pas cohérent.