c'est tres urgent!!!!!!!! les exercises sont: 28, 29, 30, 31

28)
1) C = (3x + 3) (4x - 6)
C = 12x² - 18x + 12x - 18
C = 12x² - 6x - 18

2) Pour x = 0
C = 12x² - 6x - 18
C = 12 * 0² - 6 * 0 - 18
C = 18

Pour x = 1
C = 12x² - 6x - 18
C = 12 * 1² - 6 * 1 - 18
C = 12 - 6 - 18
C = - 12

29)
1) D = (x - 7) (5x + 11)
D = 5x² + 11x - 35x - 77
D = 5x² - 24x - 77

2) Pour x = 7
D = 5x² - 24x - 77
D = 5 * 7² - 24 * 7 - 77
D = 5 * 49 - 168 - 77
D = 245 - 245
D = 0

30)
1) E = (5 - 9x) (3x - 8)
E = 15x - 40 - 27x² + 72x
E = - 27x² + 87x - 40

2) Pour x = 1
E = - 27x² + 87x - 40
E = - 24 * 1² + 87 * 1 - 40
E = - 24 + 87 - 40
E = 23

31)
1) F = 4 (7 - 5a)  + 5 (2a - 3)
F = 28 - 20a + 10a - 15
F = - 10a + 13

2) Pour a = 3/10
F = - 10 * 3/10 + 13
F = - 30/10 + 12
F = - 30/10 + 120/10
F = 90/10
F = 10 x 9 / 10 x 1
F = 9