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

#include<stdio.h>
#include<conio.h>
#include<math.h>
int main()
{
 int i, n;
 float x, S, T;
 long M, N;
 printf("\nNhap x: ");
 scanf("%f", &x);
 do
 {
 printf("\nNhap n(n >= 0) : ");
 scanf("%d", &n);
   if(n < 0)
   {
    printf("\n N phai >= 0. Xin nhap lai !");
   }
 }while(n < 0);
 S = 1;
 N = 1;
 i = 1;
 while(i <= n)
 {
  T = pow(x, (2 * i ));
  M = i * 2;
  N = N * M * (M - 1);
  S = S + T/N;
  i++;
 }
 printf("\nTong la %f", S);
 getch();
 return 0;
}