Problem Analysis #19

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20,203 toks
Problem Statement

For all x>0x > 0, let y1(x)y_1(x), y2(x)y_2(x), and y3(x)y_3(x) be the functions satisfying\frac{dy_1}{dx} - (\sin x)^2 y_1 = 0, \quad y_1(1) = 5,$$$$\frac{dy_2}{dx} - (\cos x)^2 y_2 = 0, \quad y_2(1) = 13,$$$$\frac{dy_3}{dx} - \left(\frac{2 - x^3}{x^3}\right) y_3 = 0, \quad y_3(1) = 35e,respectively. Find the value oflimx0+y1(x)y2(x)y3(x)+989xx3esinx.\lim_{x \to 0^+} \frac{y_1(x)y_2(x)y_3(x) + 989x}{x^3 e \sin x}.\

Ground Truth
989
Execution Trace
Reasoning Process

[THOUGHT] The DEs are separable. The product y1 y2 y3 = 51335*e * exp(∫_1^x [sin²t + cos²t + (2-t³)/t³] dt) = 2275 e * exp(∫_1^x 2 t^{-3} dt) = 2275 e * exp([-1/t²]_1^x) = 2275 e * exp(-1/x² + 1) = 2275 e² exp(-1/x²).

The expression is [2275 e² exp(-1/x²) + 989 x] / (x³ e sin x).

As x→0+, exp(-1/x²) → 0 faster than any power of x grows, so numerator ∼ 989 x, denominator ∼ e x⁴, ratio ∼ 989/(e x³) → +∞.

To confirm with sympy, compute the limit numerically or symbolically. [/THOUGHT] [PYTHON] import sympy as sp

x = sp.symbols('x', positive=True) e = sp.E product = 2275 * e2 * sp.exp(-1/x2) num = product + 989 * x den = x**3 * e * sp.sin(x) expr = num / den lim = sp.limit(expr, x, 0, dir='+') print(lim)

Also check numerical at small x

print(float(expr.subs(x, 0.01))) print(float(expr.subs(x, 0.001))) [/PYTHON]

Tool Output
[PYTHON OUTPUT] oo 363838831.2687578 363832827957.35803 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python output confirms the limit is oo (positive infinity). This is the ground truth value of the limit. [/THOUGHT] \boxed{\infty}

Explanation

The provided AI-generated answer concludes that the limit is (\infty), based on the Python output showing "oo" from SymPy's limit computation. The reasoning follows these steps:

  1. Solve the differential equations: Each equation is of the form ( \frac{dy}{dx} = p(x) y ), separable as ( \frac{dy}{y} = p(x) , dx ). The solutions are ( y_1(x) = 5 \exp\left( \int_1^x \sin^2 t , dt \right) ), ( y_2(x) = 13 \exp\left( \int_1^x \cos^2 t , dt \right) ), and ( y_3(x) = 35e \exp\left( \int_1^x \frac{2 - t^3}{t^3} , dt \right) ).

  2. Compute the product ( y_1(x) y_2(x) y_3(x) ): Note that ( \sin^2 t + \cos^2 t = 1 ), so ( \int_1^x (\sin^2 t + \cos^2 t) , dt = x - 1 ). For ( y_3 ), ( p_3(t) = \frac{2}{t^3} - 1 ), so ( \int_1^x p_3(t) , dt = \left[ -\frac{1}{t^2} - t \right]_1^x = -\frac{1}{x^2} - x + 2 ). Thus, ( y_1 y_2 y_3 = 5 \cdot 13 \cdot 35e \cdot \exp(x - 1) \cdot \exp\left( -\frac{1}{x^2} - x + 2 \right) = 2275 e^2 \exp\left( -\frac{1}{x^2} \right) ).

  3. Analyze the numerator: As ( x \to 0^+ ), ( \exp\left( -\frac{1}{x^2} \right) \to 0 ) faster than any polynomial, making ( y_1 y_2 y_3 \approx 0 ). The numerator simplifies to ( 989x + o(x) \sim 989x ).

  4. Analyze the denominator: ( x^3 e \sin x \sim x^3 e x = e x^4 ) as ( x \to 0^+ ), since ( \sin x \sim x ).

  5. Evaluate the limit: The expression becomes ( \frac{989x}{e x^4} = \frac{989}{e x^3} \to +\infty ) as ( x \to 0^+ ).

  6. Verify with Python: The code computes ( \lim_{x \to 0^+} \frac{2275 e^2 \exp(-1/x^2) + 989x}{x^3 e \sin x} ), yielding "oo". Numerical checks at ( x = 0.01 ) and ( x = 0.001 ) show values increasing to approximately ( 3.64 \times 10^8 ) and ( 3.64 \times 10^{11} ), confirming divergence.

This aligns with the Python output as ground truth, establishing the limit as ( +\infty ).

Final Model Output
\infty

Comparative Analysis (P19) (Average across runs)

Avg Time Taken

Gemini-3-Pro-Preview
894.8
K-EXAONE-236B-A23B
849.6
Solar-Open-100B
262.8
Deepseek-V3.2
239.3
K-EXAONE-236B-A23B
204.9
Llama-VARCO-8B-Instruct
162.1
Grok-4.1-fast
136.4
Solar-Pro-2 (31B)(high)
107.9
Kanana-2-30B-Thinking
76.7
Kanana-2-30B-Thinking-2601
68.5
GPT-5.1 (high)
51.0
A.X-4.0 (72B)
43.3
HCX-007(high)
37.2
GPT-5.2 (high)
32.8
Claude-Opus-4.5
29.2
axk1
14.8
EXAONE-4.0.1-32B (high)
5.3

Avg Token Usage

K-EXAONE-236B-A23B
70061.3
K-EXAONE-236B-A23B
41646.0
Solar-Open-100B
39496.0
Gemini-3-Pro-Preview
28664.0
Grok-4.1-fast
20203.0
Solar-Pro-2 (31B)(high)
17442.0
Kanana-2-30B-Thinking-2601
15619.5
Deepseek-V3.2
14643.0
Kanana-2-30B-Thinking
14612.0
Llama-VARCO-8B-Instruct
11147.0
A.X-4.0 (72B)
6621.0
GPT-5.1 (high)
6113.0
axk1
5991.0
Claude-Opus-4.5
5843.0
HCX-007(high)
4628.0
GPT-5.2 (high)
4356.0
EXAONE-4.0.1-32B (high)
4114.0