import math

def circle_area(radius):
    return math.pi * radius ** 2

def circle_circumference(radius):
    return 2 * math.pi * radius

def solve_quadratic(a, b, c):
    discriminant = b ** 2 - 4 * a * c
    
    if discriminant < 0:
        return None, None
    elif discriminant == 0:
        x = -b / (2 * a)
        return x, x
    else:
        x1 = (-b + math.sqrt(discriminant)) / (2 * a)
        x2 = (-b - math.sqrt(discriminant)) / (2 * a)
        return x1, x2

print(f"Circle with radius 5:")
print(f"  Area: {circle_area(5):.2f}")
print(f"  Circumference: {circle_circumference(5):.2f}")

print(f"\nQuadratic 2x² + 5x - 3 = 0:")
x1, x2 = solve_quadratic(2, 5, -3)
print(f"  Solutions: {x1:.2f}, {x2:.2f}")

print(f"\nQuadratic x² + 1 = 0:")
x1, x2 = solve_quadratic(1, 0, 1)
if x1 is None:
    print("  No real solutions")