Réponse:
a) 2(3x+1)-3 = x +9
6x + 2 -3 = x +9
6x -x = 9 +3 -2
5x = 10
5x/5 = 10/5
x = 2
b) (3x-6)(-2x+14) = 0
3x -6 = 0
3x = 6
3x/3 = 6/3
x = 2
-2x+14 = 0
-2x = -14
-2x/-2 = -14/-2
x = 7
L'équation a deux solutions : 2 ou 7
c) 2x²+11 = 1
2x² = 1 -11
2x² = -10
2x²/2 = -10/2
x² = -5
√x² = √-5
x = √-5
d) x² =15
√x² = √15
x = √15
