为方程x^3 -x^2 -1=0 在x 0 =1.5 附近的

# include <iostream>
# include <cmath>
using namespace std;
double f(double x) {
double f1,f2;
do{
f1=x*x*x-x*x-1;
f2=3*x*x+2*x;
x=x-f1/f2;
}while(fabs(x*x*x-x*x-1)>1e-5);
return x;
}
int main(){
printf("%.4lf\n", f(1.5));
return 0;
}