bonsoir,
a) (3 x + 1) - (4 x -2) = 0
3 x + 1 - 4 x + 2 = 0
- x = - 3
x = 3
b) 3 x² - 4 x = 0
x ( 3 x - 4 ) = 0
soit x = 0 , soit 3 x - 4 = 0 et x = 4/3
c) (4 x + 3)(2 - 3 x) = 6
8 x - 12 x² + 6 - 9 x = 6
- 12 x² - x = 6 - 6
- 12 x² - x = 0 donc x = 0
d) 4+ x/8 = 2 x - 3
32/8 + x /8 = 16 x /8 - 24/8
x - 16 x = - 24 - 32
- 15 x = - 56
x = 56/15
a) (5 x - 1)(2 x - 4) = 0
x = 1/5 ou 2 un des 2 facteurs est nul , voir la b
b) 25 x² - 9 = 0
( 5 x - 3 ) ( 5 x + 3) = 0 donc x = 3/5 ou - 3/5
c) 4 x² - 20 x + 25 = 0
( 2 x - 5 )² = 0
( 2 x - 5 ) ( 2 x - 5 ) = 0 donc x = 5
d) (x + 2)(x - 3) = x² +6
x² - 3 x + 2 x - 6 = x² + 6
x² - x² - x = 6 + 6
- x = 0
x = 0
