Répondre :
A = (x - 6)(x - 7) - (3x - 6)²
A = x² - 7x - 6x + 42 - (9x² - 36x + 36)
A = x² - 13x + 42 - 9x² + 36x - 36
A = -8x² - 23x + 6
(x-6)(x-7)-(3x-6)²
svp
A = (x - 6)(x - 7) - (3x - 6)²
A = x² - 7x - 6x + 42 - (9x² - 36x + 36)
A = x² - 13x + 42 - 9x² + 36x - 36
A = -8x² - 23x + 6