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
