bonjour
E = 9 x² - 12 x + 4 - 81
E = 9 x² - 12 x - 77
E = ( 3 x - 2 - 9 ) ( 3 x - 2 + 9 )
= ( 3 x - 11 ) ( 3 x + 7 )
pour x = 1/3
( 3/3 - 11 ) ( 3 /3 + 7 )
- 10 * 8
= - 80
Bonjour,
a) (3x - 2)² - 81 = 9x²-12x+4-81 = 9x²-12x-77
b) (3x - 2)² - 81 = (3x - 2)² - 9² = (3x - 2 + 9)(3x - 2 - 9) = (3x +7)(3x - 11)
c) si x=1/3, alors E = (3(1/3)-2)²-81 = (3-2)²-81 = 1 - 81 = -80
