A= 8(-2x+9)
= 8×(-2x) + 8×9
= -16x+ 72
B=(x+2) (x-3)
= x × x + x × (-3) + 2 × x +2 × (-3)
= X au carré -3x + 2x + (-6)
= X au carré -1x - 6
C= -3x × 4x + (-3x) × (-1) + 7× 4x + 7×(-1)
= -12x2 -2x + 28x +(-7)
= -12x2 + 26x -7
D= -3x × -5x -3x × 2 + 1× (-5x)+ 1× 2
= -15x2 -6x × -5x ×2
= -15x2 - 30x ×2