bonsoir
f (x) = - 0.2 x² + 0.8 x + 15.4
Δ = 0.8 ² - 4 ( - 0.2 * 15.4 ) = 12.96 = 3.6 ²
x 1 = ( - 0.8 - 3.6 ) / - 0.4 = 11
x 2 = ( - 0.8 + 3.6 ) / - 0.4 = - 7
f (x) = - 0.2 x ² + 0.8 x + 15.4
α = - 0.8 / - 0.4 = 2
β = - 0.2 * 2² + 0.8 * 2 + 15.4 = - 0.8 + 1.6 + 15.4 = 16.2
forme canonique = - 0.2 ( x - 2 ) ² + 16.2
