Bài 67

Bài 67: Tính S(x,n) =

//========================================
// Cach 1
#include <stdio.h>
#include <conio.h>

void main()
{
 float x;
 printf("x = ");
 scanf("%f", &x);
 int n;
 printf("n = ");
 scanf("%d", &n);
 float S = 0;
 float P = 1;
 float dau = -1;
 for(int i=2; i<=2*n; i=i+2)
 {
  P = P*x*x;
  S = S + P*dau;
  dau = -dau;
 }
 printf("S = %f", S);
}

//========================================
//Cach 2
#include <stdio.h>
#include <conio.h>

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

float Tong(float y, float k)
{
 float S = 0;
 float P = 1;
 float dau = -1;
 for(int i=2; i<=2*k; i=i+2)
 {
  P = P*y*y;
  S = S + P*dau;
  dau = -dau;
 }
 return S;
}