Explications étape par étape:
a)
A = 8x² + 4x² -12x - 2x + 16 - 7
= 12x² - 14x + 9
B = -14x² + 7x² + 25x - 35x - 36 + 6 - 10
= - 7x² - 10x - 40
C = -3x² - 6x² - 3x² + 3x + 6x -2 + 18
= -12x² + 9x + 16
b)
A = (12× (-1)²) - (14 × -1) + 9
= 12 + 14 + 9
= 35
B = (-7 × (-1)²) - (10× -1) - 40
= -7 + 10 - 40
= - 37
C = (-12 × (-1)²) + (9 × -1) + 16
= -12 - 9 + 16
= -5
