#Solve a quadratic equation, x**2 + bx + c = 0.
def solve_quad(b, c):
    D = (b ** 2 - 4 * c)
    x1 = (-b + D ** 0.5) / 2
    x2 = (-b - D ** 0.5) / 2
    return x1, x2
print("for b=4, c=3:", solve_quad(4, 3))
print("for b=2, c=1:", solve_quad(2, 1))
print("for b=0.5, c=4:", solve_quad(0.5, 4))
print("for b=1e10, c=3:", solve_quad(1e10, 3))
print("for b=-1e10, c=3:", solve_quad(-1e10, 4))