bonjour
a) ( 2 x + 1) ( - 5 x + 3)
= - 10 x² + 6 x - 5 x + 3 = - 10 x² + x + 3
b) ( 3 x + 1)² = 9 x² + 6 x + 1
c) ( 2 x - 1)² - 3 ( 4 x + 2)
= 4 x² - 4 x + 1 - 12 x - 6 = 4 x² - 16 x - 5
a) 3 x + 2 = 0
3 x = - 2 d'où x = - 2/3
b) 3 ( 4 x + 1) = - x - 7
12 x + 3 = - x - 7
12 x + x = - 7 - 3
13 x = - 10
x = - 10/13
c) ( 2 x + 1) ( - x + 3) = 0
soit 2 x + 1 = 0 donc x = - 1/2
soit - x + 3 = 0 donc x = 3
