Bonsoir,
F= -6x × 3x -2 × 4x
F = -18x² - 8x
G= 7 × 2x² - 5x × 4x
G = 14x² - 20x²
G = -6x²
H = - 4x 6x + 2 × 12x²
H = -24x² + 24x²
H = 0
I = - 6x × 5x + 4x × 2x
I = 30x² + 8x²
I = 38x²
J = - 5 × 3x - 3 × 2x² + 4 × 4x² + 2 × 3x
J = -15x - 6x² + 16x² + 6x
J = 10x² - 9x