Réponse:

a(x-x1)(x-x2)

a. c1= a(x-(-2))(x-4)

= a(x+2)(x-4)

De plus c1(0)= -8

a(0+2)(0-4)= -8

a× 2×(-4)= -8

a= -8/ -8= 1

c1 = 1(x+2)(x-4)

sommet (1; -9)

f(x)= a(x-1)^2 -9

f(x)= 1(x-1)^2 -9 = aussi à 1(x+2)(x-4)

c1= f(x)

b. f(0)= -8

a. c2 = a(x-(-3))(x-1)

a(x+3)(x-1)

De plus c2 (-1)=1

a(-1+3)(-1-1)= 1

a×2×(-2)=1

a=1/-4

c2= - 1/4(x+3)(x-1)

sommet (-1;1)

g(x)= a(x+1)^2 +1

g(x)= -1/4(x+1)^2 +1

c. g(3)= -3