bonjour
A = 4 x² + 2 x - 3 x - 4 x² + 9 + 8
= - x + 17
B = 8 x - 10 x + 5 x²
= 5 x² - 2 x
C = - 6 x + 15 + 2 x - 7
= - 4 x + 8
D = - 4 x² + 36 x - x + 9
= - 4 x² + 35 x + 9
E = 3 x² - 4 x + 9 - 4 x² + x - 1
= - x² - 3 x + 8
F = 21 x² - 3 - 12 x + 20 x²
= 41 x² - 12 x - 3