bonjour,
6) = a²-b² qu'on factorise (a-b)(a+b), équation produit nul
(3x+1-x-1)(3x+1+x+1) = 0
(2x)(4x+2) = 0
2x(4x+2) = 0
4x+2 =0
4x =-2
x =-2/4 =-1/2
2x =0
x = 0
7) (2x-1)(x+1)-(5x+5) = 0
et on voit que 5x=5 = 5(x+1)
on factorise :
(x+1)(2x-1-5) = 0
(x+1)(2x-6) =0
x+1 =0
x =-1
2x-6 =0
2x =-6
x = -3
10) 4x²-9 = a²-b² =(2x-3)(2x+3)
(2x-3)(2x+3-2+x) = 0
(2x-3)(3x+1) =0
2x-3 = 0
2x =3
x 3/2
3x+1 =0
x = -1/3
1) x²-6x+9 =0
= a²-2ab+b² =
(x-3)²= 0
x = 3