Problem Analysis #3

32.25s
5,079 toks
Problem Statement

Let SS be the set of all real triples (x,y,z)(x,y,z) satisfying

{x0, y0, z0,x+y2,x+2y3,x+z3,y+z3.\begin{cases} x \ge 0,\ y \ge 0,\ z \ge 0,\\[4pt] x + y \le 2,\\[4pt] x + 2y \le 3,\\[4pt] x + z \le 3,\\[4pt] y + z \le 3. \end{cases}

Define the function

F(x,y,z)=5x24y26z2+4xy2xz+3yz+20x+14y+15z+1.F(x,y,z) = -5x^2 - 4y^2 - 6z^2 + 4xy - 2xz + 3yz + 20x + 14y + 15z + 1.

Let

M=max(x,y,z)SF(x,y,z).M = \max_{(x,y,z)\in S} F(x,y,z).

Suppose MM can be written in the form M=pqM = \dfrac{p}{q} in lowest terms, where pp and qq are positive coprime integers. Find the value of p2qp^2q.

Ground Truth
44652
Execution Trace
Reasoning Process

[THOUGHT] I need to find the maximum value of the quadratic function F(x,y,z) over the feasible region S defined by the given inequalities. The constraints form a polyhedron in 3D space, and the maximum of a quadratic function over a polyhedron can occur either at a vertex or at a critical point inside the region (if it's a maximum).

My approach will be:

  1. Find all the vertices of the polyhedron S by solving the system of equations formed by the intersection of the constraint planes.
  2. Evaluate F at each vertex.
  3. Find the critical points of F inside the region by setting the gradient of F to zero and checking if the critical point is in S.
  4. Compare all these values to find the maximum M.

Let's start by finding the vertices. The constraints are:

  • x >= 0, y >= 0, z >= 0
  • x + y <= 2
  • x + 2y <= 3
  • x + z <= 3
  • y + z <= 3

The vertices are found by solving combinations of 3 equations (since we are in 3D) from the equalities of the constraints. I will use sympy to systematically find all vertices.

Then, I will define the function F and its gradient, find the critical points, and check if they are in S.

Finally, I will evaluate F at all candidate points and find the maximum M, which is supposed to be a rational number p/q. Then I will compute p^2*q. [/THOUGHT] [PYTHON] import sympy as sp import numpy as np

Define the variables

x, y, z = sp.symbols('x y z')

Define the constraints as equalities to find vertices

constraints_eq = [ x, # x = 0 y, # y = 0 z, # z = 0 x + y - 2, # x + y = 2 x + 2*y - 3, # x + 2y = 3 x + z - 3, # x + z = 3 y + z - 3 # y + z = 3 ]

Function to find vertices by solving combinations of 3 equations

def find_vertices(eq_list): vertices = [] from itertools import combinations for eqs in combinations(eq_list, 3): system = list(eqs) try: sol = sp.solve(system, (x, y, z), dict=True) if sol: sol_point = sol[0] # Check if the solution is real and non-negative if all(val.is_real and val >= 0 for val in sol_point.values()): # Check if the point satisfies all inequalities point = (sol_point[x], sol_point[y], sol_point[z]) if (point[0] + point[1] <= 2 and point[0] + 2*point[1] <= 3 and point[0] + point[2] <= 3 and point[1] + point[2] <= 3): vertices.append(point) except: pass return vertices

Find all vertices

vertices = find_vertices(constraints_eq) print("Vertices found:") for v in vertices: print(v)

Define the function F

F = -5x**2 - 4y2 - 6*z2 + 4xy - 2xz + 3yz + 20x + 14y + 15*z + 1

Evaluate F at each vertex

F_values_vertices = [] for v in vertices: F_val = F.subs({x: v[0], y: v[1], z: v[2]}) F_values_vertices.append(F_val) print(f"F at {v} = {F_val}")

Find critical points by setting gradient to zero

grad_F = [sp.diff(F, var) for var in (x, y, z)] critical_points = sp.solve(grad_F, (x, y, z), dict=True)

print("\nCritical points:") for cp in critical_points: point = (cp[x], cp[y], cp[z]) print(f"Critical point: {point}") # Check if the critical point is in the feasible region S if (point[0] >= 0 and point[1] >= 0 and point[2] >= 0 and point[0] + point[1] <= 2 and point[0] + 2*point[1] <= 3 and point[0] + point[2] <= 3 and point[1] + point[2] <= 3): print(" -> is in S") F_val = F.subs({x: point[0], y: point[1], z: point[2]}) F_values_vertices.append(F_val) print(f" F at critical point = {F_val}") else: print(" -> is NOT in S")

Find the maximum value M

if F_values_vertices: M = max(F_values_vertices) print(f"\nMaximum value M = {M}")

# Check if M is rational and in the form p/q
if M.is_rational:
    p, q = sp.fraction(M)
    print(f"M = {p}/{q} in lowest terms.")
    result = p**2 * q
    print(f"p^2 * q = {result}")
else:
    print("M is not a rational number.")

else: print("No feasible points found.") [/PYTHON]

Tool Output
[PYTHON OUTPUT] Vertices found: (0, 0, 0) (0, 0, 3) (0, 0, 3) (0, 3/2, 0) (0, 3/2, 3/2) (0, 0, 3) (2, 0, 0) (2, 0, 1) (0, 0, 3) (1, 1, 0) (1, 1, 2) (1, 1, 2) (1, 1, 2) (1, 1, 2) F at (0, 0, 0) = 1 F at (0, 0, 3) = -8 F at (0, 0, 3) = -8 F at (0, 3/2, 0) = 13 F at (0, 3/2, 3/2) = 115/4 F at (0, 0, 3) = -8 F at (2, 0, 0) = 21 F at (2, 0, 1) = 26 F at (0, 0, 3) = -8 F at (1, 1, 0) = 30 F at (1, 1, 2) = 38 F at (1, 1, 2) = 38 F at (1, 1, 2) = 38 F at (1, 1, 2) = 38 Critical points: Critical point: (1134/347, 1397/347, 594/347) -> is NOT in S Maximum value M = 38 M = 38/1 in lowest terms. p^2 * q = 1444 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python code found the vertices of the polyhedron and evaluated the function F at each vertex. The maximum value of F over the feasible region S was found to be 38, which occurs at the vertex (1, 1, 2). The code also checked for critical points by setting the gradient of F to zero, but the found critical point was outside the feasible region. Therefore, the maximum value M is 38. This is already in the form p/q = 38/1, so p=38 and q=1. The final answer is p^2 * q = 38^2 * 1 = 1444. [/THOUGHT] \boxed{1444}

Final Model Output
1444

Comparative Analysis (P3) (Average across runs)

Avg Time Taken

Solar-Open-100B
649.7
Gemini-3-Pro-Preview
236.0
K-EXAONE-236B-A23B
218.7
Kanana-2-30B-Thinking
109.4
Solar-Pro 2
93.3
Kanana-2-30B-Thinking-2601
67.5
GPT-5.2 (high)
58.9
GLM-4.5-Air
48.2
naver-hyperclovax/HCX-007
36.4
axk1
32.6
model_d_r1
27.9
EXAONE-4.0-32B
10.9

Avg Token Usage

Gemini-3-Pro-Preview
37968.3
K-EXAONE-236B-A23B
19652.0
Solar-Pro 2
16891.3
Kanana-2-30B-Thinking
16483.7
Kanana-2-30B-Thinking-2601
13774.0
axk1
13682.7
Solar-Open-100B
11324.3
GPT-5.2 (high)
8690.0
GLM-4.5-Air
6529.7
EXAONE-4.0-32B
6406.3
naver-hyperclovax/HCX-007
5829.7
model_d_r1
3390.3