Розбір

The problem can be solved in two ways:

using a loop: read $x$ and print the value of $f (x)$ on the fly;
implement $f (x)$ as a function;

Read the input data until the end of the file.

Algorithm realization

Read the input data until the end of the file.

while(scanf("%lf",&x) == 1)
{

For each test case compute and print the answer.

  y = x * x * x + 2 * x * x  - 3;
  printf("%.4lf\n",y);
}

Algorithm realization — function

Define the f function.

double f(double x)
{
  return x * x * x + 2 * x * x  - 3;
}

Read the input data until the end of the file. Compute and print the answer.

while(scanf("%lf",&x) == 1)
  printf("%.4lf\n",f(x));

Java realization

import java.util.*;

public class Main
{
  static double f(double x)
  {
    return x * x * x + 2 * x * x  - 3;
  }

  public static void main(String[] args)
  {
    Scanner con = new Scanner(System.in);
    while(con.hasNext())
    {
      double x = con.nextDouble();
      System.out.println(f(x));
    }
    con.close();
  }
}

Python realization — function

import sys

Define the f function.

def f(x):
  return x ** 3 + 2 * x * x – 3

Read the input data until the end of the file. Compute and print the answer.

for x in sys.stdin:
  x = float(x)
  print(f(x))

Python realization

import sys

Read the input data until the end of the file.

for x in sys.stdin:

For each test case compute and print the answer.

  x = float(x)
  y = x ** 3 + 2 * x * x – 3
  print(y)