Réponses

2014-04-26T13:29:35+02:00
Bonjour

A = (2x-5)² + 3(4-7x)
A = 4x² - 20x +25 + 12 - 21x
A = 4x² - 41x + 37

B = (6x-3)(4x+7) - 3(2x -8)
B = 24x² + 42x - 12x -21 - 6x + 24
B = 24x² +24x +3

C = x² -9 = (x+3)(x-3)

D= (4x-3) (2x-5) - (4 +2x)(4x-3)
D = (4x-3)(2x-5 - 4 -2x)
D = (4x-3)(-9)

4x-5 = 2 +5x
4x -5x = 2 +5
-x = 7
x = -7

(4x+7)(x-6) = 0
soit 4x+7 = 0
4x = -7
x = -7/4
soit
x-6 = 0 et x = 6

9x² +24x +16 = 0
(3x +4)(3x+4)  = 0
3x+4 = 0
3x = -4
x = -4/3