Bonsoir
5x + 4 = 7
5x = 7 - 4
5x = 3
x = 3/5
Inconnue : x
Membres : 5x + 4 et 7
6y - 4 = 2y
6y - 2y = 4
4y = 4
y = 4/4
y = 1
Inconnue : y
Membres : 6y - 4 et 2y.
a. 2x = - 6
x = - 6/2
x = - 3 → Vrai
b. 5x - 31 = - 4
5x = - 4 + 31
5x = 27
x = 27/5 → Non
c. x² - 11x = 0
x (x - 11) = 0
x = 0 et x - 11 = 0
x = 11
→ Vrai
d. x² - 4x = 5
x² - 4x - 5 = 0
(x - 5) (x + 1) = 0
x - 5 = 0 ou x + 1 = 0
x = 5 x = - 1
→ Vrai.
x + 11 = - 7
x = - 7 - 11
x = - 18
4x = 9
x = 9/4
- 5x + 9 = 3x - 12
- 5x - 3x = - 12 - 9
- 8x = - 21
x = 21/8.
