Bonjour,
9 - (2x - 1)^2 = 9 - (4x^2 - 4x + 1)
9 - (2x - 1)^2 = 9 - 4x^2 + 4x - 1
9 - (2x - 1)^2 = -4x^2 + 4x + 8
Factoriser :
9 - (2x - 1)^2 = 3^2 - (2x - 1)^2
9 - (2x - 1)^2 = (3 - 2x + 1)(3 + 2x - 1)
9 - (2x - 1)^2 = (-2x + 4)(2x + 2)
9 - (2x - 1)^2 = 4(-x + 2)(x + 1)
