Réponse :
Explications étape par étape :
Bonsoir
Rappel : delta = b² -4ac
delta<0 pas de racines
delta=0 1 racine double
delta>0 2 racines
1)
f(x) = x² + x -1
a = 1 b = 1 c = -1
delta = 1² - 4X 1 X(-1)
delta = 5
2 racines
2)
g(x) = 2x² - x - 3
a = 2 b = -1 c = -3
delta = (-1)² - 4X 2 X(-3)
delta = 25
2 racines
3)
h(x) = -5x² + 4x + 3
a = -5 b = 4 c = 3
delta = 4² - 4X (-5) X(3)
delta = 76
2 racines
4)
j(x) = x² - [tex]\sqrt{2}[/tex] x + 7
a = 1 b = - [tex]\sqrt{2}[/tex] c = 7
delta = (- [tex]\sqrt{2}[/tex])² - 4X 1 X(7)
delta = -26
Pas de racines