bonjour
f(x) = x² - 2 x - 8
Δ = ( -2)² - 4 ( 1 *- 8) = 4 + 32 = 36
x ₁ = ( 2 + 6) / 2 = 8/2 = 4
x₂ = ( 2 - 6)/2 = - 4/2 = - 2
S ( - 2 ; 4 )
g(x) = 2 x² + 3 x + 5
Δ = 3² - 4 ( 2 * 5) = 9 - 40 = - 31 ⇔ pas de solution
h(x) = 2 x² - 20 x + 50
Δ = ( -20)² - 4 ( 2 * 50) = 400 - 400 = 0 ⇔ 1 seule solution = - b /2 a = 20 /4 = 5