Bonjour, j’ai besoin de l’aide.

Bonjour

1)

K = (5x - 6)² - (5x - 6) (x + 3)

K = 25x² - 60x + 36 - (5x² + 15x - 6x - 18)

K = 25x² - 60x + 36 - 5x² - 15x + 6x + 18

K = 25x² - 5x² - 60x - 15x + 6x + 36 + 18

K = 20x² - 69x  + 54

2)

K = (5x - 6)² - (5x - 6) (x + 3)

K = (5x - 6) [(x + 3) - (5x - 6)]

K = (5x - 6) (x + 3 - 5x + 6)

K = (5x - 6) (- 4x + 9)

3) a. pour x = 0

K = (5x - 6) (- 4x + 9)

5x - 6 = 0          ou        - 4x + 9 = 0

5x = 6                            - 5x = - 9

x = 6/5                             x = 9/5

b. Pour x = 9/4

K = 20x² - 69x  + 54

K = 20 (9/4)² - 69 * 9/4 + 54

K = 20 (81/16) - 621/4 + 54

K = 1 620/16 - 621/4 + 54

K = 101,25 - 155,25 + 54

K = 101,25 - 101,25

K = 0.