#include<bits/stdc++.h>

using namespace std;

int a[10005],b[10005],c[10005];
int n;

double ans(double x,int id){
	return x*x*a[id]+x*b[id]+c[id];
}

double check(double x){
	double cnt = ans(x,1);
	for(int i = 2;i<=n;i++){
		cnt = max(cnt,ans(x,i));
	}
	return cnt;
}

int main(){
	cout<<fixed<<setprecision(4);
	int t;
	cin>>t;
	while(t--){
		cin>>n;
		for(int i = 1;i<=n;i++) cin>>a[i]>>b[i]>>c[i];
		double l = 0,r = 1005,jindu = 1e-11;
		while(r-l>jindu){
			double mid1 = l+(r-l)/3.0;
			double mid2 = r-(r-l)/3.0;
			if(check(mid1)>check(mid2)) l = mid1;
			else r = mid2;
		}
		
		cout<<check(l)<<endl;
	}	

	return 0;
}