Réponse :
bonjour
x² - 8 x + 7 = 0
Δ = 64 - 4 ( 1 x 7) = 64 - 28 = 36
x 1 = ( 8 + 6 ) / 2 = 14/2 = 7
x2 = ( 8 - 6) /2 = 2/2 = 1
2 x² + x - 3 = 0
Δ = 1 - 4 ( 2 * - 3) = 1 + 24 = 25
x 1 = ( - 1 + 5 ) / 4 = 4/4 = 1
x 2 = ( - 1 - 5)/4 = - 6/4 = - 3/2
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