#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

double f(double x);
double f1(double x);

int main()
{
	double x0=2;
	double x1=2;
	do{
		x0=x1;
		x1=x0-f(x0)/f1(x0);
				
	}while(fabs(x1-x0)>0.5*0.001);
	cout<<"根為:"<<setprecision(4)<<x1<<'\n';
	return 0;

}



double f(double x)
{
	return (x*x*x-3*x-1); 
}
double f1(double x)
{
	return (3*x*x-3); 
}