bonjour
pas de numéro précisé
x² + 1.5 x = 1
x² + 1.5 x - 1 = 0
Δ = 1.5² - 4 ( 1 * - 1 ) = 2.25 + 4 = 6.25
x 1 = ( - 1.5 - 2.5 ) / 2 = - 4/2 = - 2
x 2 = ( - 1.5 + 2.5 ) / 2 = 1/2
4 x² + 4 x = - 1
4 x² + 4 x + 1 = 0
Δ = 16 - 4 ( 4 * 1) = 16 - 16 = 0
Δ = 0 donc une solution unique = - 4 / 8 = - 1/2
x² + 3 x + 2 = 0
Δ = 9 - 4 ( 1 * 2 ) = 9 - 8 = 1
x 1 = ( - 3 - 1 ) / 2 = - 4/2 = - 2
x 2 = ( - 3 + 1 ) /2 = - 2 /2 = - 1
- x² - 4 x + 12 = 0
√ = 16 - 4 ( - 1 * 12 ) = 16 + 48 = 64
x 1 = ( 4 - 8 ) / - 2 = - 4 /- 2 = 2
x 2 = ( 4 + 8 ) / - 2 = - 12 /2 = - 6
- x² - 5 x - 36 = 0
Δ = 25 - 4 ( - 1 * - 36 ) = 25 - 144 = - 119
Δ négatif donc pas de solution dans R
- x² - 5 x + 6 = 0
Δ = 25 - 4 ( - 1 * 6 ) = 25 + 24 = 49
x 1 = ( 5 - 7 ) / - 2 = - 2 / - 2 = 1
x 2 = ( 5 + 7 ) / - 2 = - 12/2 = - 6
voilà continue , tu as suffisamment d'exemples
