Bonjour,
1. Résoudre l'équation 7x (1+3x)+(3x+1)(x-8)=0
7x + 21x^2 + 3x^2 - 24x + x - 8 = 0
24x^2 - 16x - 8 = 0
8(3x^2 - 2x - 1) = 0
3x^2 - 2x - 1 = 0
[tex]\Delta = (-2)^{2} - 4 \times 3 \times -1 = 4 + 12 = 16[/tex]
[tex]\sqrt\Delta = 4[/tex]
X1 = (2 - 4)/(2 * 3) = -2/6 = -1/3
X2 = (2 + 4)/6 = 6/6 = 1
Simplifier :
[-3 ; 5[ n [2 ; + inf [ = [2 ; 5[
[-3 ; 5[ U [2 ; + inf [ = [-3 ; +inf [
