// code 1
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <iomanip> //fixed setprecision
using namespace std;

const int N = 16;
double a[N], b[N], c[N];

int n;

double S(double x) {
    double ret = -1e100;
    for (int i = 1; i <= n; ++i) {
        ret = max(ret, a[i] * (x - b[i]) * (x - b[i]) + c[i]);
    }
    return ret;
}

void solve() {
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i] >> b[i] >> c[i];
    }
    double L = 0.0, R = 300;
    int cnt = 300;
    while (cnt--) {
        double tl = L + (R - L) / 3;
        double tr = L + (R - L) / 3 * 2;
        if (S(tl) < S(tr)) R = tr;
        else L = tl;
    }
    //printf("%.5lf\n", L);
    cout << fixed << setprecision(5) << S(L) << endl;
}

int main () {
    int T; cin >> T;
    for (int i = 0; i < T; ++i) {
        solve();
    }
}

//code 2

#include <bits/stdc++.h>
using namespace std;

int a[16];
vector<int> sta;
int n;

void dfs(int now, int cnt) {
    //try to push a[now]
    if (cnt == 6) {
        for (int i = 0; i < 6; ++i) {
            cout << sta[i] << ' ';
        }
        cout << endl;
        return;
    }
    if (now == n + 1) {
        return;
    }
    sta.push_back(a[now]);
    dfs(now + 1, cnt + 1);
    sta.pop_back();
    dfs(now + 1, cnt);
}

int main () {
    while (scanf("%d", &n)) {
        if (n == 0) break;
        for (int i = 1; i <= n; ++i) {
            scanf("%d", &a[i]);
        }
        dfs(1, 0);
    }
}