Bài 68

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 = x;
 float T = x;
 float dau = -1;
 for(int i=3; i<=2*n+1; i=i+2)
 {
  T = T*x*x;
  S = S + T*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 = y;
 float T = y;
 float dau = -1;
 for(int i=3; i<=2*k+1; i=i+2)
 {
  T = T*y*y;
  S = S + T*dau;
  dau = -dau;
 }
 return S;
}