[tex]bonjour \\ a = (5x - 1)(x + 3) + (5x - 1) {}^{2} \\ a = (5x - 1) \times (x + 3 + 5x - 1) \\ a = (5x - 1) \times (6x + 2) \\ a = (5x - 1) \times 2(3x + 1) \\ a = 2(5x - 1) \times (3x + 1) \\ \\ b = 25x {}^{2} - 49 \\ b = {5}^{2} {x}^{2} - {7}^{2} \\ b = (5 x {)}^{2} - {7}^{2} \\ b = (5x - 7) \times (5x + 7)[/tex]
