// A polynomial function with default arguments
#include <iostream>
using namespace std;

double poly(double, double, double = 0., double = 0., double = 0.);

int main() {

  double x;
  cout << "Input x: ";
  cin >> x;

  cout << "2.3 - 5.4 x                     = "
       << poly(x,2.3,-5.4) << endl;

  cout << "2.3 - 5.4 x + 1.4 x^2           = "
       << poly(x,2.3,-5.4,1.4) << endl;

  cout << "2.3 - 5.4 x + 1.4 x^2 + 0.8 x^3 = "
       << poly(x,2.3,-5.4,1.4,0.8) << endl;

}

double poly(double x, double a, double b, double c, double d) {
  return a + b*x + c*x*x + d*x*x*x;
}