Répondre :
Bonsoir,
A=(x-7)(2x+3)
A = 2x^2 + 3x - 14x - 21
A = 2x^2 - 11x - 21
calculer la valeur de A pour x =1/2
A = 2 * (1/2)^2 - 11 * 1/2 - 21
A = 2 * 1/4 - 11/2 - 21
A = 1/2 - 11/2 - 42/2
A = 1/2 - 53/2
A = -52/2
A = -26
A=(x-7)(2x+3)
A = 2x^2 + 3x - 14x - 21
A = 2x^2 - 11x - 21
calculer la valeur de A pour x =1/2
A = 2 * (1/2)^2 - 11 * 1/2 - 21
A = 2 * 1/4 - 11/2 - 21
A = 1/2 - 11/2 - 42/2
A = 1/2 - 53/2
A = -52/2
A = -26