Bonsoir,
A = -x × x - x × (-5) + 2 × x + 2 × (-5)
=-x² + 5x + 2x - 10 = -x² + 7x - 10
B = 2x × 6 + 2x × (-x) - 7 × 6 - 7 × (-x)
12x - 2x² - 42 + 7x = - 2x² + 19x - 42
C = 8 × 3x + 8 × (-2) - 3x × 3x - 3x × (-2)
= 24x -16 - 9x² + 6x = -9x² + 30x - 16
D = - 2x × (-x) - 2x × 9 + 1 × (-x) + 1 × 9
= 2x² - 18x - x + 9 = 2x² - 19x + 9