Bài 18: Tính S(n) = 1 + x^2/2! + x^4/4! + ... + x^2n/(2n)!

#include <stdio.h>
#include <conio.h>
#include <math.h>
int main()
{
 long n = 2;
 float x = 3;
 float S = 0, T, M = 1;
 int i = 2, j = 1;
 while(i <= 2 * n)
 {
  T = pow(x, i);
  M = M * i * j;
  S = S + T / M;
  i = i + 2;
  j = j + 2;
 }
 printf("S = %2.3f", S + 1);
 getch();
}

Code chạy: while -> printf

2 <= 2 * 2 = 4:

T = x^2, M = 1.1.2, S = x^2 / (1.2)

4 <= 2 * 2 = 4:

T = x^4, M = 1.1.2.4.3, S = x^2 / (1.2) + x^4 / (1.2.3.4)

5 <= 4 dừng thoát in S = x^2 / (1.2) + x^4 / (1.2.3.4) + 1 = 8.875