>>> polynome_degre2(1,1,0)
['Deux solutions réelles :', -1.0, 0.0]
>>> polynome_degre2(25,-4,1/4)
['Deux solutions complexes :', (0.08-0.06j), (0.08+0.06j)]
>>> polynome_degre2(1,-14,49)
['Une solution réelle :', 7.0]