Bonjour
A = (x + 3)² + 3 (2x + 1)²
A = x² + 6x + 9 + 3 (4x² + 4x + 1)
A = x² + 6x + 9 + 12x² + 12x + 3
A = x² + 12x² + 6x + 12x + 9 + 3
A = 13x² + 18x + 12
B = (x - 6)² - (2x + 2)²
B = x² - 12x + 36 - (4x² + 8x + 4)
B = x² - 12x + 36 - 4x² - 8x - 4
B = x² - 4x² - 12x - 8x + 36 - 4
B = - 3x² - 20x + 32
C = 70x + 100 + (8x + 9) (2x - 12)
C = 70x + 100 + 16x² - 96x + 18x - 108
C = 16x² + 70x + 18x - 96x + 100 - 108
C = 16x² - 8x - 8.
