>>598
複利計算なんかに縁がないのであってるかは知らんが
#include <stdio.h>
#include <math.h>

double f(double rate)
{
    return pow(1.0+rate,10)-2.0; /*f(x)*/
}
double g(double rate)
{
    return 10.0*pow(1+rate,9); /*f'(x)*/
}
int main()
{
    const double eps = 0.0000001;
    const int maxloop = 30;
    double xb,xa;
    int i;

    xb = xa = 1.0;
    for(i=0; i<maxloop; i++){
        xa = xb - f(xb)/g(xb);
        if(fabs(xa-xb)<eps) break;
        xb = xa;
    }

    printf("%f\n",xa);
    return 0;
}