Aidez moi svp c'est important

bonjour,

f(x) = (3x+2)²-5(3x+2)
(9x²+12x+4)-(15x+10) =
9x²+12x+4-15x-10 =
9x²-3x-6

1) developpe et reduis (3x+2)(3x-3) tu dosi (re)trouver 9x²-3x-6

2) f(x) = (3x+2)²-5(3x+2)
(9x²+12x+4)-(15x+10) =
9x²+12x+4-15x-10 =
9x²-3x-6

3) résoudre f(x) = 0
forme factorisée, équation produit nul

(3x+2)(3x-3) = 0
3x+2 = 0
3x = -2
x =-2/3
3x-3 = 0
3x = 3
x = 1

f(x) = -6
9x²-3x-6 = -6
9x²-3x-6+6 = 0
3x(3x-1) = 0
3x-1 = 0
3x =1
x =1/3
3x =0
x = 0

f(x) = x(3x+2)
(3x+2)(3x-3) = x(3x+2)
(3x+2)(3x-3)-x(3x+2) = 0
(3x+2)(3x-3-x) = 0
(3x+2)(2x-3) = 0
3x=2  =0
3x =-2
x =-2/3
2x-3 = 0
2x = 3
x =3/2