Verified answer

#include <iostream>

#include <math.h>

using namespace std;

float f_1(float x, int n)

{

   float result = 0;

   for(int k = 1; k <= n; k ++)

       result += (sin(k * x) + sin((k*x - 1)/2))/exp(x - 1.0/k);

   return result * sqrt(n * M_PI);

}

float f_2(float x, int n)

{

   float result = 1.0;

   for(int k = 1; k <= n; k ++)

       result *= pow(pow(x, k - 1.0)/(k + 1.0/3.0), 1.0/k) + 0.5;

   return sqrt(x)* log(x) - result;

}

float f_3(float x, int n)

{

   float result = 0;

   for(int k = 1; k <= n; k ++)

       result += pow(exp(k + sqrt(x))*cos(2.0*x/k), 1.0/k);

   return sqrt(abs(x) + n) * result;

}

float f_4(float x, int n)

{

   float result = 1.0;

   for(int k = 1; k <= n; k ++)

       result *= sqrt(x*x * pow(log(n),k/2.0))/(k + 4.0/3.0);

   return exp(x) - sin(x) + result;

}

float f_5(float x, int n)

{

   float result = 0;

   for(int k = 1; k <= n; k ++)

       result += pow(x, k - 1.0)/(abs(log(k*x*x))+2.0/3.0);

   return (x*x + pow(x, 1.0/3.0)) *result;

}

int main()

{

   cout.setf(ios::fixed);

   float x;

   int n;

   cout << "Vvedite x, n" << endl;

   cin >> x >> n;

   cout << "f_1(x, n) = " << f_1(x,n)<< endl;

   cout << "f_2(x, n) = " << f_2(x,n)<< endl;

   cout << "f_3(x, n) = " << f_3(x,n)<< endl;

   cout << "f_4(x, n) = " << f_4(x,n)<< endl;

   cout << "f_5(x, n) = " << f_5(x,n)<< endl;

   return 0;

}