Réponse :
Explications étape par étape
Bonsoir
1) Developper :
A(x) = (x^2 - 25) - 2(5 - x) (x + 6)
A(x) = x^2 - 25 - (10 - 2x)(x + 6)
A(x) = x^2 - 25 - (10x + 60 - 2x^2 - 12x)
A(x) = x^2 - 25 + 2x^2 + 2x - 60
A(x) = 3x^2 + 2x - 85
2) factoriser :
A(x) = (x - 5)(x + 5) - 2(5 - x)(x + 6)
A(x) = (x - 5)(x + 5) + 2(x - 5)(x + 6)
A(x) = (x - 5)(x + 5 + 2(x + 6))
A(x) = (x - 5)(x + 5 + 2x + 12)
A(x) = (x - 5)(3x + 17)
3) développer la forme factorisee :
A(x) = 3x^2 + 17x - 15x - 85
A(x) = 3x^2 + 2x - 85
4) choisir l’expression pour calculer :
A(V2) ; A(5) ; A(-6) ; A(2 - V3) ; A(1/V2)
A(V2) = 3 * (V2)^2 + 2V2 - 85
A(V2) = 6 + 2V2 - 85
A(V2) = -79 + 2V2
A(5) = (5 - 5)(3 * 5 + 17)
A(5) = 0 * (15 + 17)
A(5) = 0
A(-6) = (-6 - 5)(3 * -6 + 17)
A(-6) = (-11)(-18 + 17)
A(-6) = -11 * (-1)
A(-6) = 11
A(2 - V3) = 3 * (2 - V3)^2 + 2(2 - V3) - 85
A(2 - V3) = 3 * (4 - 4V3 + 3) + 4 - 2V3 - 85
A(2 - V3) = 3 * (7 - 4V3) + 4 - 2V3 - 85
A(2 - V3) = 21 - 12V3 - 81 - 2V3
A(2 - V3) = -60 - 14V3
A(1/V2) = 3 * (1/V2)^2 + 2 * (1/V2) - 85
A(1/V2) = 3/2 + 2/V2 - 85
A(1/V2) = 3/2 - 170/2 + 2/V2
A(1/V2) = -167/2 + 2V2/(V2)^2
A(1/V2) = -167/2 + V2