forme canonique : ax² + bx + c = a(x-alpha)²+beta
alpha = -b/2a
beta = -(b-4ac)²/2a
a)
a = 1
b = -8
c = 9
alpha = 8/2×1 = 8/2 = 4
beta = -(-8-4×1×9)²/2×1 = (8+4×9)²/2 = (8+36)²/2 = 44²/2 = 1936 = 968
forme canonique : 1(x-4)²+968
b)
a = -2
b = 6
c = 1
alpha = -6/2×(-2) = -6/-4 = 1,5
beta = -(6-4×(-2)×1)²/2×(-2) = -(6-(-8))²/-4 = -(6+8)²/-4 = 196/-4 = -49
forme canonique : -2(x-1,5)²-49
c)
a = 16
b = 0
c = -1
alpha = 0/2×16 = impossible
forme canonique impossible
