Bonjour
On considère l'expression:
F= (5x - 3 )(3x+2) - (5x -3)²
a)Développer et réduire F.
F= (5x - 3 )(3x+2) - (5x -3)²
F = 15x² + 10x - 9x - 6 - (25x² - 30x + 9)
F = 15x² + 10x - 9x - 6 - 25x² + 30x - 9
F = 15x² - 25x² + 10x - 9x + 30x - 6 - 9
F = - 10x² + 31x - 15.
b)Factoriser F
F= (5x - 3 )(3x+2) - (5x -3)²
F = (5x - 3) [(3x + 2) - (5x - 3)]
F = (5x - 3) (3x + 2 - 5x + 3)
F = (5x - 3) (- 2x + 5)
