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