Bonjour,
3a+b = 17
7a+b = 33
Par combinaison:
7a+b - 3a-b = 33-17
4a = 16
a = 4
7×4+b = 33
28+b = 33
b = 33-28 = 5
f(x) = 4x+5
Donc après tu calcules f(x) = 37 ; f(x) = 9 ; f(x) = 17 et f(x) = 29 pour avoir le code secret.
4x + 5 = 37
4x = 37 - 5
4x = 32
x = 32/4
x = 8
4x + 5 = 9
4x = 9 - 5
x = 4/4
x = 1
4x + 5 = 17
4x = 17 - 5
4x = 12
x = 12/4
x = 3
4x + 5 = 29
4x = 29 - 5
x = 24/4
x = 6
Le code est : 8136