task2.cpp

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

using std::cout;
using std::cin;
using std::endl;

int main(void)
{
  double m, r, result;

  cout  << "\n\t Input m, r ";
  cin >> m >> r;

  if((r <= m) && (m <= 2*r)){
    result = sqrt(fabs(3*m - 5*r)) * exp(m/r);
  } else {
    if( m > 2*r ){
      result = sqrt(fabs(3*m + 5*r)) * exp(r/m);
    } else {
      cout << "\n\t ERROR!" << endl;
      return 1;
    }
  }

  cout << "\n\t Result: rez = " << result << endl;


  // uncomment under windows
  // cout << "\n Press any key ... " << endl;
  // getch();

  return 0;
}

$ c++ task2.cpp; ./a.out 

     Input m, r 6 5

     Result: rez = 8.7842

$ c++ task2.cpp; ./a.out 

     Input m, r 5 1

     Result: rez = 5.46228

http://i.imm.io/19iqa.png