for a, b, c being Real st a <> 0 & delta (a,b,c) >= 0 holds
for x being Real holds
( not Polynom (a,b,c,x) = 0 or x = ((- b) + (sqrt (delta (a,b,c)))) / (2 * a) or x = ((- b) - (sqrt (delta (a,b,c)))) / (2 * a) )