python计算二次方程的实根

#计算二次方程的实根程序
import math

def fun():
    print("This program finds the real solutions to a quadraic\n")
    a,b,c=eval(input("please enter the coefficients(a,b,c):"))
    delta=b*b-4*a*c
    if a==0:
        x=-b/c
        print("\nThere is an solution", x)
    elif delta<0:
        print("The equation has no real roots!")
    elif delta==0:
        x=-b/(2*a)
        print("\nThere is a double root at",x)
    else:
        discRoot=math.sqrt(b*b-4*a*c)
        root1=(-b+discRoot)/(2*a)
        root2=(-b-discRoot)/(2*a)
        print("\nThe solutions are:",x1, x2)

if __name__ =='__main__':
    fun()