bonsoir
X ⁴ - 6 x² + 8 = 0
X² - 6 x + 8 = 0
Δ = ( - 6 )² - 4 ( 1 *8) = 36 - 32 = 4
x 1 = ( 6 - 2 ) / 2 = 4/2 = 2
x 2 = ( 6 + 2 ) /2 = 8 /2 = 4
x² = 2 ⇔ x = √2 ou - √2
x² = 4 ⇔ x = √4 ou - √4 = 2 ou - 2
S { - 2 ; 2 ; - √2 ; √ 2 )
X ⁴ + x² + 1 = 0
X² + x + 1 = 0
Δ = 1 ² - 4 ( 1 * 1 ) = 1 - 4 = - 3
Δ < 0 pas de solutions