bonjour
A (x) = 2 x - 6 + 8 x - 36 = 10 x - 42
B (x) = 15 x² + 24 x + 5 x + 8 = 15 x² + 29 x + 8
C (x) = 5 x - 5 + 15 x - 6 x² + 10 - 4 x = - 6 x² + 16 x + 5
D (x) = x - 3 + 4 x + 8 + 5 ( 2 x - 4 x² + 6 - 12 x )
D (x) = 5 x + 5 + 10 x - 20 x² + 30 - 60 x
D ( x )= - 20 x² - 45 x + 35