bonsoir
forme 1 = forme canonique
forme 2 = factorisée
forme 3 = développée
f (x) = 3 ( x - 1 /2 )² - 27/ 4
= 3 ( x² - 2 x /2 + 1/4 ) - 27/4
= 3 x² - 6 x /2 + 3/4 - 27/4
= 3 x² - 3 x - 6
f (x) = 3 ( x + 1 ) ( x - 2 )
= ( 3 x + 3 ) ( x - 2 )
= 3 x² - 6 x + 3x - 6
= 3 x² - 3 x - 6
f (x) = 3 x² - 3 x - 6
f (0) = 0 - 0 - 6 = - 6
f (x) = 0
3 ( x + 1 ) ( x - 2 ) = 0
x = - 1 ou 2
f ( 1/6) = f ( 5/6 )
f (1/6) = 3 ( 1/6)² - 3 * 1/6 - 6 = 3 * 1/36 - 3 /6 - 6 = 3/36 + 18/36 - 216/36
= 195/36
f ( 5/6 ) = 3 ( 5/6 )² - 3 *5/6 - 6 = 3*25/36 - 15/6 - 6 = 75/36 - 90/36 - 216/36
= - 231/36
