Réponse :

A = 8x² - 10x + 3 - 2x² + 13x + 24 = 6x² + 3x + 27

B = 27x - 40x² - 28x - 20 - 35x² + 25x = - 75x² + 24x - 20

C = -20 + 6x - 21x² + 41x - 6x² = - 27x² + 47x - 20

D = 18x² + 9x - 8x - 4 + 81x² - 36x - 36x + 16 = 99x² - 71x + 12

E = 2x² - 23x + 63 + 6x + 27 = 2x² -  17x + 90

F = 84x - 42x²  + 4 - 2x + 35x + 5 - 6x - x = - 42x² + 112x + 9