bonjour
x² + 11 x + 30 = 0
Δ = 121 - 4 ( 1 * 30 ) = 121 - 120 = 1 = 1 ²
x 1 = ( - 11 - 1 ) / 2 = - 12 /2 = - 6
x 2 = ( - 11 + 1 ) / 2 = - 10 /2 = - 5
f (x) = ( x + 6 ) ( x + 5 )
3 x² + 8 x - 3 = 0
Δ = 64 - 4 ( 3 * - 3) = 64 + 36 = 100 = 10 ²
x 1 = ( - 8 - 10 ) / 6 = - 16/6 = - 8/3
x 2 = ( - 8 + 10 ) / 6 = 2/6 = 1/3
f (x) = 3 ( x + 8/3 ) ( x - 1 /3 )
2 x² - 4 x + 5 = 0
Δ = 16 - 4 ( 2 *5 ) = 16 - 40 = - 24
Δ < 0 donc pas de solution
