Bài 4

Tính S(n) = 1/2 + 1/4 + 1/6 + ... + 1/(2n)

//========================================
//Cách 1

#include <stdio.h>
#include <conio.h>

void main()
{
 int n;
 printf("n = ");
 scanf("%d", &n);
 float S = 0;
 int i = 2;
 while (i <= 2*n)
 {
  S = S + (float)1/i;
  i = i + 2;
 }
 printf("S = %f", S);
}

//========================================
//Cách 2

#include <stdio.h>
#include <conio.h>

float Tong(int);
void main()
{
 int n;
 printf("n = ");
 scanf("%d", &n);
 float kq = Tong(n);
 printf("S = %f", kq);
}

float Tong(int k)
{
 float S = 0;
 for (int i=2; i<=2*k; i=i+2)
 {
  S = S + (float)1/i;
 }
 return S;
}