#include <iostream>
#include <queue>
#include <stdio.h>
#include <vector>

using namespace std;

int main(){
    freopen("sequences.in", "r", stdin);
    freopen("sequences.out", "w", stdout);

    int q;
    cin>>q;
    for(int i=0; i<q; i++){
        int b1, b2, c1, c2, s1, s2, n;
        //scanf("%d %d %d %d %d %d %d", &b1, &c1, &s1, &b2, &c2, &s2, &n);
        cin>>b1>>c1>>s1>>b2>>c2>>s2>>n;

        priority_queue<long long, vector<long long>, greater<long long>> q;

        for(int j=s1; j<s1+n; j++){
            long long res = j*j + b1*j + c1;
            q.push(res);
        }
        for(int j=s2; j<s2+n; j++){
            long long res = j*j + b2*j + c2;
            q.push(res);
        }
        int shown = 1;
        while(shown < n){
            q.pop();
            shown++;
        }
        //printf("#ll\n", q.top());
        cout<<q.top()<<endl;
    }
}
/*
2
0 1 1 1 0 2 3
2 -2 0 1 1 0 4


*/