2
1
2 0 0
2
2 0 0
2 -4 2

0.0000
0.5000

#include <bits/stdc++.h>
//#pragma comment(linker, "/STACK:102400000, 102400000")
using namespace std;
const int maxn = 10005;
const int inf = 0x3f3f3f3f;
const double eps = 1e-9;
int a[maxn], b[maxn], c[maxn];
int n;

double func(double x){
	double maxnum=-inf, f;
	for (int i=0; i<n; ++i){
		f = a[i]*x*x+b[i]*x+c[i];
		maxnum = max(maxnum, f);
	}
	return maxnum;
}

int main(){
	#ifdef LOCAL
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
	#endif
	int T;
	scanf("%d", &T);
	while (T--){
		scanf("%d", &n);
		for (int i=0; i<n; ++i)
			scanf("%d%d%d", a+i, b+i, c+i);
		double l=0.0, r=1000.0, mid, tri;
		while (r-l > eps){
			mid = (r+l)/2.0;
			tri = (r+mid)/2.0;
			if (func(mid) > func(tri))
				l = mid;
			else
				r = tri;
		}
		double ans = func(l);
		printf("%.4f\n", ans);
	}
	return 0;
}