bjr
49x² - 36 - (7x - 6)(2x - 3) =
(7x)² - 6² - (7x - 6)(2x - 3) = (a² - b² = ....)
(7x - 6)(7x + 6) - (7x - 6)(2x - 3) = (facteur commun (7x - 6)
(7x - 6)(7x + 6) - (7x - 6)(2x - 3) =
(7x - 6)[(7x + 6) - (2x - 3)] =
(7x - 6)(7x + 6 - 2x + 3) =
(7x - 6)(5x + 9)