Bonjour
B = 3 * 5x * 2x = 15x * 2x = 30x²
C = 4 * (- 2x) * 5 = - 8x * 5 = - 40x
D = x * 8 * 2x = 8x * 2x = 16x
E = 3 * x * 2x = 3x * 2x = 6x²
F = 7 * 4 * 2x = 28 * 2x = 56x
G = 2 * (- 7x) * (- 3) = - 14x * (- 3) = 42x
H = 3 * 5x * 2x = 15x * 2x = 30x² (idem B!)
I = 2 * (- 6x) * 3x = - 12x * 3x = - 36x²
J = 4 * 10x * 6x = 40x * 6x = 240x²