Bonsoir,
A = x * 8x
A = 8x²
B = 6x * 2x
B = 12x²
C = 9 + (- 9x + 2) * (- 4x + 8)
C = 9 + 36x² - 72x - 8x + 16
C = 36x² - 72x - 8x + 9 + 16
C = 36x² - 80x + 25
D = (- 8x - 10) * (- 5x - 10) + 3
D = 40x² + 80x + 50x + 100 + 3
D = 40x² + 130x + 103
E = - 8x + 7 + (2x + 2) * (10x + 6)
E = - 8x + 7 + 20x² + 12x + 20x + 12
E = 20x² - 8x + 12x + 20x + 7 + 12
E = 20x² + 24x + 19