# 第二题 import sys import math T = int(sys.stdin.readline().strip()) ABCs = [] for i in range(T): line = sys.stdin.readline().strip() values = list(map(int, line.split())) ABCs.append(values) for i in range(T): a = ABCs[i][0] b = ABCs[i][1] c = ABCs[i][2] if (4 * a * a - 8 * a * b * c) <= 0: print(0) continue y1 = (2 * a + math.sqrt(4 * a * a - 8 * a * b * c)) / (2 * b) y2 = (2 * a - math.sqrt(4 * a * a - 8 * a * b * c)) / (2 * b) if y1 < y2: y1, y2 = y2, y1 s1 = (1 / (2 * b)) * y1 * y1 - (c / b) * y1 - (1 / (6 * a)) * y1 * y1 * y1 s2 = -(1 / (2 * b)) * y2 * y2 + (c / b) * y2 + (1 / (6 * a)) * y2 * y2 * y2 print(s1 + s2)