rt 求调

#include <bits/stdc++.h>                        
using namespace std;
typedef long long ll;
const double eps=1e-8; 
ll n,a[10000],b[10000],c[10000];
double f(double x){
	double ans=INT64_MIN;
	for(int i=0;i<n;i++) ans=max(ans,x*x*a[i]+x*b[i]+c[i]);
	return ans;
}
int main(){
	ll T;
	cin>>T;
	while(T--){
		cin>>n;
		for(int i=0;i<n;i++) cin>>a[i]>>b[i]>>c[i];
		double l=0,r=1000;
		while(r-l>=eps){
			double lmid=l+(r-l)/3,rmid=l+2*(r-l)/3;
			if(f(lmid)<f(rmid)) r=rmid;
			else l=lmid;
		}
		cout<<fixed<<setprecision(4)<<l<<'\n';
	}
}