Can you solve this equation?（二分）

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <iostream>   
using namespace std; 
double result(double x)
{
   return 8*pow(x,4)+7*pow(x,3)+2*pow(x,2)+3*x+6;   
}
int main()
{  
    //freopen("in.txt","r",stdin);
   // freopen("out.txt","w",stdout);
    int t,i;
    double y,x,l,r,mid;
    scanf("%d",&t);
    while(t--)
    {
      scanf("%lf",&y);
      if(result(0.0)>y||result(100.0)<y)
      {
          printf("No solution!\n");                       
      }   
      else
      {
      
         l=0.0;r=100.0;
         while(r-l>1e-7)
         {
           mid=(l+r)/2;
           if(result(mid)>y)
             r=mid-1e-7;                         
           else
             l=mid+1e-7;           
         }
         printf("%.4lf\n",l);
      }   
    }
return 0;
}