exercice 1 Résous le système suivant : 3x + y = 1 x – 2y = 3 3x + 2y = 29 2x + 3y = 31

3x+y =1
x-2y =3
donc
x-2y =3
x = 2y+3

3x+y =1
3(2y+3) +y = 1
6y +9 +y =1
7y = 1-9
7y = -8
y = -8/7

x = 2y+3
x = 2(-8/7) +3
x = -16/7 +3
x = -16/7 +21/3
x = 5/3

tu fais la meme chose pour la 2eme