bonjour
f(x) = 2 x² + 4 x - 1
α = - 4/4 = - 1
β = 2 ( -1)² + 4 ( -1) - 1 = 2 - 4 - 1 = - 1
f(x) = 2 ( x + 1)² - 1
g(x) = 4 x² - 12 x + 9
α = 12/8 = 3/2
β = 4 ( 3/2)² - 12 ( 3/2) + 9
= 4 -9/4 - 36/2 + 9
= - 36/4 - 72/4 + 36/4 = - 72/4 = - 18
g(x) = 4 ( x - 3/2)² - 18