Python to solve equations

Python goes well with math, you know!
So... how do you solve an equation of second degree?

from math import sqrt

x1=0
x2=0
def solve(a=0,b=0,c=0):
    global x1,x2
    'solve the equation'
    delta = (b**2)-(4*a*c)
    print("Delta=",delta)
    if delta < 0:
        print("There are no solutions, delta is negative")
        x1 = 'Nan'
        x2= 'Nan'
    else:
        x1 = (-b+sqrt(delta))/(2*a)
        x2 = (-b-sqrt(delta))/(2*a)
        return x1,x2

solve(2,-5,-3)  # Change the parameters here

print("\nx1 =",x1,"\n\nx2 =",x2)

Delta= 49

x1 = 3.0 

x2 = -0.5