Bonsoir
1) Developper :
H = (4x - 1)(5x - 3) - (4x - 1)^2
H = 20x^2 - 12x - 5x + 3 - (16x^2 - 8x + 1)
H = 20x^2 - 16x^2 - 17x + 8x + 3 - 1
H = 4x^2 - 9x + 2
2) factoriser :
H = (4x - 1)(5x - 3 - 4x + 1)
H = (4x - 1)(x - 2)
3) calculer H pour x = 1/2 :
H = (4 * 1/2 - 1)(1/2 - 2)
H = (2 - 1)(1/2 - 4/2)
H = 1 * (-3/2)
H = (-3/2)
4) résoudre : (4x - 1)(x - 2) = 0
4x - 1 = 0 ou x - 2 = 0
4x = 1 ou x = 2
x = 1/4 ou x = 2
