Problem Analysis #2

Solar-Pro 2 · Run 1

14.83s
5,340 toks
Problem Statement

Let

f(z)=z2,f(z) = z^{2},

and consider the upper semicircular arc

C:z=52eiθ,0θπ.C : z = \frac{5}{2} e^{i\theta}, \qquad 0 \le \theta \le \pi.

Let

L={xR:52x52},L = \{\, x \in \mathbb{R} : -\tfrac{5}{2} \le x \le \tfrac{5}{2} \,\},

and form the closed contour

Γ=CL,\Gamma = C \cup L,

where CC is traversed from z=52z = \tfrac{5}{2} to z=52z = -\tfrac{5}{2}, and LL is traversed from x=52x = -\tfrac{5}{2} to x=52x = \tfrac{5}{2}.\

Suppose the contour integral

Cf(z)dz=pq,\int_C f(z)\, dz=-\frac{p}{q},

where pp and qq are positive integers which are relatively prime. Find p+qp+q.

Ground Truth
137
Execution Trace
Reasoning Process

[THOUGHT] To compute the contour integral of f(z)=z2f(z) = z^2 over the upper semicircular arc CC, we can use two approaches: direct parametrization of CC or leveraging the closed contour Γ=CL\Gamma = C \cup L. Since f(z)f(z) is entire, the integral over the closed contour Γ\Gamma is zero. Thus, the integral over CC is the negative of the integral over LL.

First, compute the integral over LL (the real line segment from 5/2-5/2 to 5/25/2):

Lf(z)dz=5/25/2x2dx=[x33]5/25/2=12512.\int_L f(z) \, dz = \int_{-5/2}^{5/2} x^2 \, dx = \left[ \frac{x^3}{3} \right]_{-5/2}^{5/2} = \frac{125}{12}.

Therefore, the integral over CC is 12512-\frac{125}{12}.

To verify, parametrize CC as z(θ)=52eiθz(\theta) = \frac{5}{2} e^{i\theta} for 0θπ0 \leq \theta \leq \pi. Then:

dz=52ieiθdθ,f(z)=(52eiθ)2=254ei2θ.dz = \frac{5}{2} i e^{i\theta} d\theta, \quad f(z) = \left( \frac{5}{2} e^{i\theta} \right)^2 = \frac{25}{4} e^{i2\theta}.

The integral becomes:

Cf(z)dz=0π254ei2θ52ieiθdθ=1258i0πei3θdθ.\int_C f(z) \, dz = \int_0^\pi \frac{25}{4} e^{i2\theta} \cdot \frac{5}{2} i e^{i\theta} d\theta = \frac{125}{8} i \int_0^\pi e^{i3\theta} d\theta.

Evaluating the integral:

0πei3θdθ=[ei3θ3i]0π=ei3π13i=23i=2i3.\int_0^\pi e^{i3\theta} d\theta = \left[ \frac{e^{i3\theta}}{3i} \right]_0^\pi = \frac{e^{i3\pi} - 1}{3i} = \frac{-2}{3i} = \frac{2i}{3}.

Thus, the integral over CC is:

1258i2i3=12582i23=1258(23)=12512.\frac{125}{8} i \cdot \frac{2i}{3} = \frac{125}{8} \cdot \frac{2i^2}{3} = \frac{125}{8} \cdot \left( \frac{-2}{3} \right) = -\frac{125}{12}.

Both methods confirm the result. The fraction 12512-\frac{125}{12} has p=125p = 125 and q=12q = 12, which are coprime. Therefore, p+q=137p + q = 137.

[/THOUGHT] [PYTHON]

Calculate the integral over L

from sympy import symbols, integrate

x = symbols('x') integral_L = integrate(x**2, (x, -5/2, 5/2)) result = -integral_L print(result) [/PYTHON]

Tool Output
[PYTHON OUTPUT] -10.4166666666667 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python output is 10.4166666666667-10.4166666666667, which equals 12512-\frac{125}{12}. Here, p=125p = 125 and q=12q = 12 are coprime, so p+q=137p + q = 137. [/THOUGHT] 137\boxed{137}

Final Model Output
137

Comparative Analysis (P2) (Average across runs)

Avg Time Taken

Gemini-3-Pro-Preview
56.5
HCX-007
42.2
K-EXAONE-236B-A23B
39.8
Kanana-2-30B-Thinking
35.4
GLM-4.5-Air
29.0
Kanana-2-30B-Thinking-2601
28.5
Solar-Open-100B
16.1
Solar-Pro 2
15.4
GPT-5.2 (high)
10.0
EXAONE-4.0-32B
9.0

Avg Token Usage

Gemini-3-Pro-Preview
8640.0
Kanana-2-30B-Thinking-2601
7490.0
Kanana-2-30B-Thinking
7071.0
HCX-007
5399.3
Solar-Pro 2
5336.0
Solar-Open-100B
4666.0
K-EXAONE-236B-A23B
4476.7
GLM-4.5-Air
3903.0
EXAONE-4.0-32B
3641.0
GPT-5.2 (high)
3069.0