6.py

import sys
import cmath
import math

def get_float(msg,allow_zero):
    x=None
    while x is None:
        try:
            x=float(input(msg))
            if not allow_zero and abs(x)<sys.float_info.epsilon:
                print('zero is not allowed')
                x=None
        except ValueError as err:
            print(err)
    return x

print("ax\N{SUPERSCRIPT TWO}+bx+c=0")
a=get_float("enter a:",False)
b=get_float("enter b:",True)
c=get_float("enter c:",True)

x1=None
x2=None
discriminant=(b**2)-4*a*c
if discriminant==0:
    x1=-b/(2*a)
else:
    if discriminant>0:
        root=math.sqrt(discriminant)
    else:
        root=cmath.sqrt(discriminant)
    x1=(-b+root)/(2*a)
    x2=(-b-root)/(2*a)

def to_int(a):
    if a.is_integer():
        return int(a)
    return a

equation=("{0}x\N{SUPERSCRIPT TWO}+{1}x+{2}=0"
          "\N{RIGHTWARDS ARROW} x={3:.2f}".format(to_int(a),to_int(b),to_int(c),x1))
if x2 is not None:
    equation += " or x={:.2f}".format(x2)

print(equation)