Problem Analysis #20

117.12s
13,814 toks
Problem Statement

Let a function f(x)f(x) defined on the set of all real numbers satisfyf(x)=xsin(πx)for x[0,2],f(x) = x \sin(\pi x) \qquad \text{for } x \in [0,2],andf(x)=2f(x2)for all real x.f(x) = 2 f(x-2) \qquad \text{for all real } x.Consider the region enclosed by the curve y=f(x)y = f(x), the line y=21012(x2026),y = 2^{1012}(x - 2026),and the two vertical lines x=2026x = 2026 and x=2027x = 2027.The area of this region is equal to21012(p+qπ+r3π),2^{1012}\left(p + \frac{q}{\pi} + \frac{r\sqrt{3}}{\pi}\right),for some rational numbers p,q,rp, q, r.Find the value of 2028 $$\cdot$$ p $$\cdot$$ q $$\cdot$$ r.oindent

Ground Truth
1352
Execution Trace
Reasoning Process

The problem asks for the area of the region enclosed by the curve y=f(x)y = f(x), the line y=21012(x2026)y = 2^{1012}(x - 2026), and the vertical lines x=2026x = 2026 and x=2027x = 2027.

First, I derived the expression for f(x)f(x) on the interval [2026,2027][2026, 2027]. Given f(x)=2f(x2)f(x) = 2 f(x-2), we have f(x)=2kf(x2k)f(x) = 2^k f(x-2k). For x[2026,2027]x \in [2026, 2027], let k=1013k = 1013. Then x2k=x2026[0,1]x - 2k = x - 2026 \in [0, 1]. Thus, f(x)=21013f(x2026)f(x) = 2^{1013} f(x - 2026). Since x2026[0,1][0,2]x - 2026 \in [0, 1] \subset [0, 2], we use the base definition f(u)=usin(πu)f(u) = u \sin(\pi u). So, f(x)=21013(x2026)sin(π(x2026))f(x) = 2^{1013} (x - 2026) \sin(\pi (x - 2026)).

Let t=x2026t = x - 2026. As xx goes from 20262026 to 20272027, tt goes from 00 to 11. The functions in terms of tt are: Curve: y1(t)=21013tsin(πt)y_1(t) = 2^{1013} t \sin(\pi t) Line: y2(t)=21012ty_2(t) = 2^{1012} t

The area is given by A=01y1(t)y2(t)dtA = \int_{0}^{1} |y_1(t) - y_2(t)| dt. A=0121013tsin(πt)21012tdtA = \int_{0}^{1} |2^{1013} t \sin(\pi t) - 2^{1012} t| dt A=21012012tsin(πt)tdtA = 2^{1012} \int_{0}^{1} |2 t \sin(\pi t) - t| dt A=2101201t2sin(πt)1dtA = 2^{1012} \int_{0}^{1} t |2 \sin(\pi t) - 1| dt

The problem states A=21012(p+qπ+r3π)A = 2^{1012} \left( p + \frac{q}{\pi} + \frac{r\sqrt{3}}{\pi} \right). So I need to compute K=01t2sin(πt)1dtK = \int_{0}^{1} t |2 \sin(\pi t) - 1| dt and express it in the form p+qπ+r3πp + \frac{q}{\pi} + \frac{r\sqrt{3}}{\pi}.

I will use Python to compute this integral symbolically.

[PYTHON] from sympy import symbols, sin, pi, integrate, Abs, sqrt, simplify

t = symbols('t', real=True)

Define the integrand part without the absolute value

expr = t * (2 * sin(pi * t) - 1)

Determine where 2sin(pit) - 1 is positive/negative in [0, 1]

sin(pit) = 1/2 at pit = pi/6 and 5*pi/6 => t = 1/6 and 5/6

In [0, 1/6], sin(pi*t) < 1/2, so expression is negative.

In [1/6, 5/6], sin(pi*t) > 1/2, so expression is positive.

In [5/6, 1], sin(pi*t) < 1/2, so expression is negative.

Split the integral

I1 = integrate(-expr, (t, 0, 1/6)) I2 = integrate(expr, (t, 1/6, 5/6)) I3 = integrate(-expr, (t, 5/6, 1))

total_integral = simplify(I1 + I2 + I3) print(total_integral) [/PYTHON]

Tool Output
[PYTHON OUTPUT] (-4*sin(0.166666666666667*pi) - 0.166666666666667*pi**2 + 4*sin(0.833333333333333*pi) + pi*(-2.0 + 0.666666666666667*cos(0.166666666666667*pi) - 3.33333333333333*cos(0.833333333333333*pi)))/pi**2 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The previous output used floating point numbers for fractions, leading to an inexact representation. I need to re-compute the integral using exact rational arithmetic in SymPy to match the form p+qπ+r3πp + \frac{q}{\pi} + \frac{r\sqrt{3}}{\pi}.

The integral is K=01t2sin(πt)1dtK = \int_{0}^{1} t |2 \sin(\pi t) - 1| dt. Splitting the domain [0,1][0, 1] based on where 2sin(πt)12\sin(\pi t) - 1 changes sign:

  • [0,1/6][0, 1/6]: 2sin(πt)1<0    ...=12sin(πt)2\sin(\pi t) - 1 < 0 \implies |...| = 1 - 2\sin(\pi t)
  • [1/6,5/6][1/6, 5/6]: 2sin(πt)1>0    ...=2sin(πt)12\sin(\pi t) - 1 > 0 \implies |...| = 2\sin(\pi t) - 1
  • [5/6,1][5/6, 1]: 2sin(πt)1<0    ...=12sin(πt)2\sin(\pi t) - 1 < 0 \implies |...| = 1 - 2\sin(\pi t)

So K=01/6(t2tsin(πt))dt+1/65/6(2tsin(πt)t)dt+5/61(t2tsin(πt))dtK = \int_{0}^{1/6} (t - 2t\sin(\pi t)) dt + \int_{1/6}^{5/6} (2t\sin(\pi t) - t) dt + \int_{5/6}^{1} (t - 2t\sin(\pi t)) dt.

I will compute this exactly. [/THOUGHT] [PYTHON] from sympy import symbols, sin, pi, integrate, Rational, sqrt, simplify

t = symbols('t')

Define the integrand parts

Region 1: [0, 1/6], integrand is t - 2tsin(pit)

term1 = t - 2tsin(pi*t) I1 = integrate(term1, (t, 0, Rational(1, 6)))

Region 2: [1/6, 5/6], integrand is 2tsin(pit) - t

term2 = 2tsin(pi*t) - t I2 = integrate(term2, (t, Rational(1, 6), Rational(5, 6)))

Region 3: [5/6, 1], integrand is t - 2tsin(pit)

term3 = t - 2tsin(pi*t) I3 = integrate(term3, (t, Rational(5, 6), 1))

total_integral = simplify(I1 + I2 + I3) print(total_integral) [/PYTHON]

Tool Output
[PYTHON OUTPUT] (-12 - pi + 12*sqrt(3))/(6*pi) [/PYTHON OUTPUT]
Reasoning Process

The area of the region is given by the integral of the absolute difference between the curve y=f(x)y = f(x) and the line y=21012(x2026)y = 2^{1012}(x - 2026) over the interval [2026,2027][2026, 2027]. Let t=x2026t = x - 2026. The interval becomes t[0,1]t \in [0, 1]. The function is f(x)=21013tsin(πt)f(x) = 2^{1013} t \sin(\pi t) and the line is y=21012ty = 2^{1012} t. The area is: [ A = \int_{0}^{1} |2^{1013} t \sin(\pi t) - 2^{1012} t| dt = 2^{1012} \int_{0}^{1} t |2 \sin(\pi t) - 1| dt ] Using Python, we computed the integral K=01t2sin(πt)1dtK = \int_{0}^{1} t |2 \sin(\pi t) - 1| dt and found: [ K = -\frac{1}{6} - \frac{2}{\pi} + \frac{2\sqrt{3}}{\pi} ] Comparing this to the form p+qπ+r3πp + \frac{q}{\pi} + \frac{r\sqrt{3}}{\pi}, we identify: [ p = -\frac{1}{6}, \quad q = -2, \quad r = 2 ] We are asked to find the value of 2028pqr2028 \cdot p \cdot q \cdot r: [ 2028 \cdot p \cdot q \cdot r = 2028 \cdot \left(-\frac{1}{6}\right) \cdot (-2) \cdot 2 = 2028 \cdot \frac{4}{6} = 2028 \cdot \frac{2}{3} ] [ 2028 \cdot \frac{2}{3} = 676 \cdot 2 = 1352 ]

\boxed{1352}

Final Model Output
1352

Comparative Analysis (P20) (Average across runs)

Avg Time Taken

Solar-Pro-2 (31B)(high)
209.1
Llama-VARCO-8B-Instruct
194.6
Gemini-3-Pro-Preview
117.1
A.X-4.0 (72B)
98.1
Grok-4.1-fast
91.6
HCX-007(high)
65.9
GPT-5.1 (high)
59.3
Deepseek-V3.2
40.9
Claude-Opus-4.5
27.1
EXAONE-4.0.1-32B (high)
7.6

Avg Token Usage

Grok-4.1-fast
15328.0
Gemini-3-Pro-Preview
13814.0
Solar-Pro-2 (31B)(high)
12507.0
HCX-007(high)
7833.0
GPT-5.1 (high)
7486.0
Deepseek-V3.2
7264.0
Llama-VARCO-8B-Instruct
7065.0
Claude-Opus-4.5
5400.0
EXAONE-4.0.1-32B (high)
5036.0
A.X-4.0 (72B)
3005.0