用c语言求表达式1/2+1/4+1/6+1/8+…求N项的和

Answer 1

#include<stdio.h>

int main()

{ int n,i;

  double s=0;

  scanf("%d",&n);

  for(i=1;i<=n;i++)

    s+=1.0/(i+i);

  printf("%f\n",s);

  return 0;

}

Answer 2

#include <stdio.h>
int main()
{
double f=1;
int i;
for(i=1;i<=25;i++)
f=f+pow(-1,i)*((double)1/(2*i));
printf("%6.2f\n",f);
return 0;
}
#include<stdio.h>
#include<math.h>
main()
{
int n=0;
double sum=1,k=-0.5,t=1,m;
while(fabs(t)>0.0001)
{
t=t*k;
m=t;
sum=sum+m;
n++;
}
printf("n=%d ,sum=%lf\n",n,sum);
}