# WA 想定
from decimal import *
import sys
from math import *

input=sys.stdin.readline
write=sys.stdout.write

N=int(input())
Ans=[None]*N
getcontext().prec=7

for n in range(N):
    T,mu,L=map(Decimal,input().split())
    V=36*(-5*mu*T+Decimal(sqrt(5*mu*(L+5*mu*T*T))))/5
    V=str(V)

    if ("." not in V):
        V+=".00"
    elif V.index(".")==len(V)-2:
        V+="00"

    V=V[:V.index(".")+3]
    Ans[n]=V

write("\n".join(map(str,Ans)))