can someone assist me with my newton raphson code

[erry04]

hi all,i just learn about newton raphson method and im thinking to create a code for it.(im not expert in c++,so my code could be wrong)
For the function and it derivative,i hard code it in my program.
im using:
f(x)=-0.6x^2+2.4x+5.5
f'(x)=-1.2x+2.4
eps=0.00001
initial guess=input by user

the problem is something wrong with the answer.Can someone assist me???

#include<iostream>
#include<cmath>
using namespace std;
double NRM(double x0,double eps);
double f_one(double x);
double f_one_prime(double x);
double equation_1(double x0);
double temp_criterion(double x0,double x_new);

int main()
{
	double x0,root,eps=0.00001;

	cout<<"enter the initial guess:";
	cin>>x0;
	if((f_one(x0)!=0) && (f_one_prime(x0)!=0))
	{
		root=NRM(x0,eps);
	}
	cout<<"Root is taken as:" << root<<endl;

	getchar();
	getchar();
}
double f_one(double x)
{
	return(-0.6*x*x+2.4*x+5.5);
}
double f_one_prime(double x)
{
	return(-1.2*x+2.4);
}
double NRM(double x0,double eps)
{
	double x_new,c_t,i=0;
	x_new=0;
	c_t=temp_criterion(x0,x_new);

	do
	{
		x_new=equation_1(x0);
		c_t=temp_criterion(x0,x_new);
		cout<<"i="<<i++<<"|"<<"xi="<<x0<<"|"<<"temp criterion="<<c_t<<endl;
		x0=x_new;
	}while(c_t>eps);
	return(x_new);
}
double temp_criterion(double x0,double x_new)
{
	return((abs(x_new-x0))/abs(x_new));
}
double equation_1(double x0)
{
	double term;

	term=f_one(x0)/f_one_prime(x0);
	return(x0-term);
	
}

[newb16]

f(x)=-0.6x^3+2.4x^2+5 .5
f'(x)=-1.2x^2+2.4

Derivative is wrong and doesn't match what is in the code. Then, if initial guess is right or derivative is 0, you print garbage that sits in root and not what's required.

[erry04]

oh,i mistype my function,it should be
f(x)=-0.6x^2+2.4x+5.5
f'(x)=-1.2x+2.4

[newb16]

For initial guesses 0 and 2.2 it finds -1.628 and 5.628 as roots that seems to be right.
So if you feel that "something wrong with the answer." and no more details, then you only have to "change something in the code".