bonsoir
f (x) = 2 x² - 5 x + 4
f ( 1) = 2 *1² - 5 *1 + 4 = 1 - 5 + 4 = 0
f (√3) = 2 ( √2)² - 5 √3 + 4 = 4 - 5 √3 + 4 = 8 - 5 √3
A ( -4) = 2 ( - 4 )² - 5 *-4 + 4 = 32 + 24 = 56 donc A ∉ C
g (x) = - 3 x + 5
g ( - 5/6 ) = - 3 * - 5/6 + 5 = 15/6 + 30/6 = 45/6
- 3 x + 5 = 1
- 3 x = - 4
x = 4/3