Bonjour,
a) 5(7x - 3) = 12x - 11
35x -15 =12x -11
35x -12x = -11+15
23x = 4
x= 4/23
b) (4x - 8)(5x + 6) = 20x² + 4x - 12
20x² +24x -40x -48= 20x² +4x -12
20x² -20x² +24x -40x -4x = -12 +48
-20x = 36
x= -36/20 = - 18/10 = -9/5
Réponse :
bonjour
a) 5 ( 7 x - 3 ) = 12 x - 11
35 x - 15 = 12 x - 11
35 x - 12 x = - 11 + 15
23 x = 4
x = 4/23
b) ( 4 x - 8 ) ( 5 x + 6 ) = 20 x² + 4 x - 12
20 x² + 24 x - 40 x - 48 = 20 x² + 4 x - 12
20 x² - 16 x - 48 = 20 x² + 4 x - 12
20 x² - 20 x² - 16 x - 4 x = - 12 + 48
- 20 x = 36
x = - 36/20 = - 9/5
Explications étape par étape
