public static void Main()
Console.WriteLine("ax3+bx2+cx+d");
int a = Convert.ToInt32(Console.ReadLine());
int b = Convert.ToInt32(Console.ReadLine());
int c = Convert.ToInt32(Console.ReadLine());
int d = Convert.ToInt32(Console.ReadLine());
double x0test = (a*x0)*(a*x0)*(a*x0)+(b*x0)*(b*x0)+c*x0+d;
double x1test = (a*x1)*(a*x1)*(a*x1)+(b*x1)*(b*x1)+c*x1+d;
if ((x0test < 0) && (x1test < 0)){
fx0 = (a*x0)*(a*x0)*(a*x0)+(b*x0)*(b*x0)+c*x0+d;
fx1 = (a*x1)*(a*x1)*(a*x1)+(b*x1)*(b*x1)+c*x1+d;
} while((fx0 < 0) && (fx1 < 0));
Console.WriteLine("Промежуток между " + x0 + " и " + x1);
fxn1 = (a*xn1)*(a*xn1)*(a*xn1)+(b*xn1)*(b*xn1)+c*xn1+d;
Console.WriteLine("fxn = " + fxn1);
xn1 = xn1 - ((fxn1*(xn1-x0))/(fxn1-fx0));
Console.WriteLine("xn = " + xn1);
Console.WriteLine("X = " + xn1);
if ((x0test > 0) && (x0test > 0)){
fx0 = (a*x0)*(a*x0)*(a*x0)+(b*x0)*(b*x0)+c*x0+d;
Console.WriteLine("fx0 " + fx0);
fx1 = (a*x1)*(a*x1)*(a*x1)+(b*x1)*(b*x1)+c*x1+d;
Console.WriteLine("fx1 " + fx1);
} while((fx0 > 0) && (fx1 > 0));
Console.WriteLine("Промежуток между " + x0 + " и " + x1);
fxn = (a*xn)*(a*xn)*(a*xn)+(b*xn)*(b*xn)+c*xn+d;
Console.WriteLine("fxn = " + fxn);
xn = xn - ((fxn*(xn-x0))/(fxn-fx0));
Console.WriteLine("xn = " + xn);
Console.WriteLine("X = " + xn);