Bonjour
a. 2x + 4 = - x + 28
2x + x = 28 - 4
3x = 24
x = 24/3
x = 8
b. 10x + 3 = 5x + 45
10x - 5x = 45 - 3
5x = 42
x = 42/5
x = 8,4
c. x² + 2x + 20 = 100
x² + 2x + 20 - 100 = 0
x² + 2x - 80 = 0
(x - 8) (x + 10) = 0
x - 8 = 0 ou x + 10 = 0
x = 8 x = - 10
d. - 2x² + 8 = - 15x
- 2x² + 8 + 15x = 0
-(x - 8) (2x + 1) = 0
x - 8 = 0 ou 2x + 1 = 0
x = 8 2x = - 1
x = - 1/2
Marion a tort.
