Réponse :
bonsoir
x² - 8 x + 15 = 0
Δ = 64 - 4 ( 1 * 15 ) = 64 - 60 = 4
x 1 = ( 8 - 2 ) / 2 = 6/2 = 3
x 2 = ( 8 + 2 ) /2 = 5
- 3 x² + 12 x + 15 = 0
Δ = 144 - 4 ( - 3 *15 ) = 144 + 180 = 324
x 1 = ( - 12 - 18 ) / - 6 = - 30 / - 6 = 5
x 2 = ( - 12 + 18 ) /- 6 = 6 / -6 = - 1
4 ( x² + 4 x + 4 ) - 64 = 4 x² + 16 x + 16 - 64 = 4 x² + 16 x - 48
Δ = 256 - 4 ( 4 * - 48 ) = 256 + 768 = 1 024
x 1 = ( - 16 - 32 ) / 8 = - 48/8 = - 6
x 2 = ( - 16 + 32 ) /8 = 16 /8 = 2
Explications étape par étape :
