三分查找

#include<bits/stdc++.h>
using namespace std;
const double eps=1e-6;
double y;
double check(double x){
    return pow(x,7)*6+pow(x,6)*8+pow(x,3)*7+pow(x,2)*5-x*y;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%lf",&y);
//        cin>>y;
        double l,r,midl,midr;
        l=0,r=100;
        while(r-l>eps){
            midl=(l+r)/2;
            midr=(midl+r)/2;
            if(check(midl)>check(midr)) l=midl;
            else r=midr;
        }
        printf("%.4f\n",check((r+l)/2));
    }
}