#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;
double f(double );
double qiuxielv(double);
double root(double,double);
void main()
{
    double x0,x1,x;
    cout<<"please input x0:"<<endl;
    cin>>x0;
    x=root(x0,x1);
    cout<<setiosflags(ios::fixed)<<setprecision(7);
    cout<<"the root of the equation is "<<x<<endl;
}
double f(double x)
{
    double y;
    y=((x+2)*x+3)*x+4;
    return y;
}
double qiuxielv(double x)
{
    double y;
    y=(3*x+4)*x+3;
    return y;
}
double root(double x0,double x1)
{
    double f0,f2;
    do
    {
        f0=f(x0);
        f2=qiuxielv(x0);
        x1=x0-f0/f2;
        x0=x1;
    }while(fabs(x1-x0)>=1e-6);
   
     return x0;
}