#include <bits/stdc++.h>

using namespace std;

void input(string f)
{
	string one = f + ".in";
	string two = f + ".out";

	freopen(one.c_str(), "r", stdin);
	freopen(two.c_str(), "w", stdout);	
}

inline unsigned long long calc(unsigned long long x, unsigned long long b, unsigned long long c){
	return x*x + b*x + c;
}

unsigned long long bin_search(unsigned long long num, unsigned long long b, unsigned long long c, unsigned long long s, unsigned long long n, unsigned long long l, unsigned long long r){
	unsigned long long mid;

	while(l != r){
		mid = (l + r) / 2;

		if(calc(mid, b, c) > num){
			r = mid;
		}
		else{
			l = mid + 1;
		}
	}

	return l - s;
}

void solve(){
	unsigned long long b1, c1, s1, b2, c2, s2, n;

	cin >> b1 >> c1 >> s1 >> b2 >> c2 >> s2 >> n;

	unsigned long long l = s1, r = s1 + n, mid, l2 = s2, r2 = s2 + n;

	while(l != r){
		mid = (l + r) / 2;

		unsigned long long ans = bin_search(calc(mid, b1, c1), b2, c2, s2, n, l2, r2);

		if(ans + mid - s1 + 1 >= n){
			r = mid;
			r2 = ans + s2;
		}
		else{
			l = mid + 1;
			l2 = ans + s2;
		}
	}

	mid = l;

	if(bin_search(calc(mid, b1, c1), b2, c2, s2, n, l2, r2) + mid - s1 + 1 == n){
		cout << calc(mid, b1, c1) << "\n";

		return ;
	}

	l = s2, r = s2 + n, mid;
	l2 = s1, r2 = s1 + n;

	while(l != r){
		mid = (l + r) / 2;

		unsigned long long ans = bin_search(calc(mid, b2, c2), b1, c1, s1, n, l2, r2);

		if(ans + mid - s2 + 1 >= n){
			r = mid;
			r2 = ans + s1;
		}
		else{
			l = mid + 1;
			l2 = ans + s1;
		}
	}

	mid = l;

	cout << calc(mid, b2, c2) << "\n";

	return ;
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(NULL);

	input("sequences");

	unsigned long long q;

	cin >> q;

	for(unsigned long long i = 0; i < q; i++){
		solve();
	}

	return 0;
}