Réponse :
Explications étape par étape
Bonsoir
Developper :
C = (5/2 x - 1/3)(5/2 x + 1/3)
C = (a - b)(a + b)
C = a^2 - b^2
C = (5/2 x)^2 - (1/3)^2
C = 25/4 x^2 - 1/9
C = 25x^2/4 - 1/9
D = (4/7 - x)^2
D = (4/7)^2 - 2 * 4/7 * x + x^2
D = 16/49 - 8/7 x + x^2
D = x^2 - 8x/7 + 16/49