Bonjour
Exercice 1:
A)(X+1)(X-3)=0
x + 1 = 0 ou x - 3 = 0
x = - 1 x = 3
B)(X-7)(2X+1)=0
x - 7 = 0 ou 2x + 1 = 0
x = 7 2x = - 1
x = - 1/2
C)X au carré -81=0
(x)² - (9)² = 0
(x - 9) (x + 9) = 0
x - 9 = 0 ou x + 9 = 0
x = 9 x = - 9
D)(X+5)² =4
(x + 5)² - 4 = 0
(x + 5)² - (2)² = 0
(x + 5 - 2) (x + 5 + 2) = 0
(x + 3) (x + 7) = 0
x + 3 = 0 ou x + 7 = 0
x = - 3 x = - 7
(X+1)(2X+3)+(X+1)(3X-2)=0
(x + 1) (2x + 3 + 3x - 2) = 0
(x + 1) (5x + 1) = 0
x + 1 = 0 ou 5x + 1 = 0
x = - 1 5x = - 1
x = - 1/5
F)(2X+3)(2X-4)=X² -4
(2x + 3) (2x - 4) - x² + 4 = 0
(2x + 3) (2x - 4) - (x - 2) (x + 2) = 0
(x - 2) (3x + 4) = 0
x - 2 = 0 ou 3x + 4 = 0
x = 2 3x = - 4
x = - 4/3