import math

def real_roots (a, b, c):
    d = b**2 - 4*a*c
    x1 = (-b + math.sqrt(d)) / (2*a)
    x2 = (-b - math.sqrt(d)) / (2*a)
    return x1, x2

def has_real_roots (a, b, c):
    d = b**2 - 4*a*c
    return d >= 0

def is_a_root(a, b, c, x, eps):
    return abs(a*x**2+b*x+c) <= eps