Réponse :
I = 3(4x + 7) + 4(2x - 9)
= 3 * 4x + 3 * 7 + 4 * 2x - 4 * 9
= 12x + 21 + 8x - 36
= 12x + 8x + 21 - 36
= 20x + (-15)
= 20x - 15
J = 7x(2x - 5) - x(3x - 1)
= 7x * 2x - 7x * 5 - x * 3x - x * 1
= 14x² - 35x - 3x² - x
= 14x² - 3x² - 35x - x
= 11x² - 34x
K = (3x - 2)(2x - 5)
= 3x * 2x - 3x * 5 - 2 * 2x - 2 * 5
= 6x² - 15x - 4x - 10
= 6x² - 11x - 10
L = (2x + 3)(5x - 8) - (2x - 4)(5x - 1)
= 2x * 5x + 2x * 8 - 3 * 5x - 3 * 8 - 2x * 5x - 2x * 1 - 4 * 5x - 4 * 1
= 10x² + 16x - 15x - 16 - 10x² - 2x - 20x - 4
= 10x² - 10x² + 16x - 15x - 2x - 20x - 16 - 4
= -1x - 12