Bonjour voici tes réponses :)
Bonjour;
1)
-4x² -12
2)
3x² -12x
3)
-14x +42
x = 11+7
x = 18
x = 16/5
x =3,2
x = 18*3
x = 54
9x = 17+8
9x = 25
x = 25/9