❔ How to create a cubic function calculator that also calculates the minimum and maximum value

Console.WriteLine("Please enter a, b, c, d for the cubic function ax^3+bx^2+cx+d");

            Console.WriteLine("Input the value for a");

            double a = Convert.ToDouble(Console.ReadLine());

            Console.WriteLine("Input the value for b");

            double b = Convert.ToDouble(Console.ReadLine());

            Console.WriteLine("Input the value for c");

            double c = Convert.ToDouble(Console.ReadLine());

            Console.WriteLine("Input the value for d");

            double d = Convert.ToDouble(Console.ReadLine());

            double x_min, x_max;

            double f1 = 3 * a; // multiply 3 by the first input
            double f2 = 2 * b; // multiply 2 times by the second input
            double f3 = c; // associate the value of c to f3

            double discriminant = f2 * f2 - 4 * f1 * f3;  // formula for cubic function (delta)

            if (discriminant < 0) // if discriminant is less that 0 it will output "The function has no relative maxima or minima."
            {
                Console.WriteLine("The function has no relative maxima or minima.");
            }
            else
            {
                x_min = (-f2 - Math.Sqrt(discriminant)) / (2 * f1); // formula to find the minimum value of x
                x_max = (-f2 + Math.Sqrt(discriminant)) / (2 * f1); // formula to find the maximum value of x

                double y_min = a * x_min * x_min * x_min + b * x_min * x_min + c * x_min + d; 
                double y_max = a * x_max * x_max * x_max + b * x_max * x_max + c * x_max + d;

                Console.WriteLine("The relative minimum of the function is: ({0}, {1})", x_min, y_min);
                Console.WriteLine("The relative maximum of the function is: ({0}, {1})", x_max, y_max); 

Console.WriteLine("Please enter a, b, c, d for the cubic function ax^3+bx^2+cx+d");

            Console.WriteLine("Input the value for a");

            double a = Convert.ToDouble(Console.ReadLine());

            Console.WriteLine("Input the value for b");

            double b = Convert.ToDouble(Console.ReadLine());

            Console.WriteLine("Input the value for c");

            double c = Convert.ToDouble(Console.ReadLine());

            Console.WriteLine("Input the value for d");

            double d = Convert.ToDouble(Console.ReadLine());

            double x_min, x_max;

            double f1 = 3 * a; // multiply 3 by the first input
            double f2 = 2 * b; // multiply 2 times by the second input
            double f3 = c; // associate the value of c to f3

            double discriminant = f2 * f2 - 4 * f1 * f3;  // formula for cubic function (delta)

            if (discriminant < 0) // if discriminant is less that 0 it will output "The function has no relative maxima or minima."
            {
                Console.WriteLine("The function has no relative maxima or minima.");
            }
            else
            {
                x_min = (-f2 - Math.Sqrt(discriminant)) / (2 * f1); // formula to find the minimum value of x
                x_max = (-f2 + Math.Sqrt(discriminant)) / (2 * f1); // formula to find the maximum value of x

                double y_min = a * x_min * x_min * x_min + b * x_min * x_min + c * x_min + d; 
                double y_max = a * x_max * x_max * x_max + b * x_max * x_max + c * x_max + d;

                Console.WriteLine("The relative minimum of the function is: ({0}, {1})", x_min, y_min);
                Console.WriteLine("The relative maximum of the function is: ({0}, {1})", x_max, y_max);