#include <stdio.h>
#include <math.h>

double f(double x) {
  return x - 0.2 * (pow(x, 2) + 6);
}

double solve(double x0, double eps) {
  double x = x0;
  int iter = 0;

  while (fabs(0.2 * (pow(x, 2) + 6) - x) > eps) {
    x = 0.2 * (pow(x, 2) + 6);
    iter++;
  }

  printf("Итераций: %d\n", iter);
  return x;
}

int main() {
  double x0 = 0;
  double eps =1e-20;
  double root = solve(x0, eps);

  printf("Решение: x = %lf\n", root);
  printf("Значение f(x) = %lf\n", f(root));

  return 0;
}