Bonsoir,
1)
f(-10) = 12 * (-10)² - 4 * (-10) - 5 = 1200 + 40 - 5 = 1235
f(0) = 12 * 0² - 4 * 0 - 5 = -5
f(5/6) = 12 * (5/6)² - 4 * (5/6) - 5 = 2 * 25 / 6 - 2 * 5 / 3 - 5 = 25/3 - 10/3 - 15/3 = (25 - 10 - 15) / 3 = 0
f(17) = 12 * 17² - 4 * 17 - 5 = 3395
2)
a)
(6x - 5)(2x + 1) = 12x² + 6x - 10x - 5 = 12x² - 4x - 5 = f(x)
(6x - 5)(2x + 1) = f(x)
b) f(x) = (6x - 5)(2x + 1) = 0
6x - 5 = 0 ou 2x + 1 = 0
6x = 5 ou 2x = -1
x = 5/6 ou x = -1/2
Bonne soirée.
