bonjour
1. A = 5 x - 4 x² + 2 - 5 x + 6 - 3 x²
= - 7 x² + 8
2. B = 6 x ( 3 x - 5 ) - 4 x²
= 18 x² - 30 x - 4 x²
= 14 x² - 30 x
3. C = 6 x² - 7 x
= x ( 6 x - 7 )
4. D = 3 x² - 5 x + 8
si x = - 2 , d = 3 ( - 2 )² - 5 ( -2 ) + 8 = 12 + 10 + 8 = 30
bonne journée