Problem Analysis #1

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Problem Statement

Evaluate the integral

I=P(x)eix(x20569i)8dx,I = \int_{-\infty}^{\infty} \frac{P(x)e^{ix}}{\left(x-\frac{205}{69}i\right)^{8}}\,dx,

where

P(x)=x714ix6+(8560i)x5(240+210i)x4+(420840i)x3(560+1680i)x2+(13442688i)x+3840.\begin{aligned} P(x)=\,&x^{7}-14ix^{6}+(85-60i)x^{5}-(240+210i)x^{4} \\ &+(420-840i)x^{3}-(560+1680i)x^{2} \\ &+(1344-2688i)x+3840. \end{aligned}

If I=a+biI=a+bi, compute 10a+b\lfloor 10a \rfloor + \lfloor b \rfloor.

Ground Truth
9
Execution Trace
Reasoning Process

[THOUGHT] Let me analyze this integral. We have an integral of the form: I=P(x)eix(x20569i)8dxI = \int_{-\infty}^{\infty} \frac{P(x)e^{ix}}{(x-\frac{205}{69}i)^{8}} dx

The pole is at x=20569ix = \frac{205}{69}i, which is in the upper half-plane (since 20569>0\frac{205}{69} > 0).

For integrals of the form f(x)eixdx\int_{-\infty}^{\infty} f(x)e^{ix} dx where f(x)f(x) is a rational function, we close the contour in the upper half-plane (since eix=ei(x+iy)=eixeye^{ix} = e^{i(x+iy)} = e^{ix}e^{-y} decays as y+y \to +\infty).

By the residue theorem: I=2πiResz=20569iP(z)eiz(z20569i)8I = 2\pi i \cdot \text{Res}_{z=\frac{205}{69}i} \frac{P(z)e^{iz}}{(z-\frac{205}{69}i)^{8}}

For a pole of order 8, the residue is: Res=17!limzz0d7dz7[P(z)eiz]\text{Res} = \frac{1}{7!} \lim_{z \to z_0} \frac{d^7}{dz^7}[P(z)e^{iz}]

Let me compute this using Python. [/THOUGHT] [PYTHON] import sympy as sp from sympy import I, pi, exp, factorial, floor, re, im, Rational

Define the variable

x = sp.Symbol('x')

Define P(x)

P = (x7 - 14Ix6 + (85 - 60*I)x**5 - (240 + 210I)x**4 + (420 - 840I)x**3 - (560 + 1680I)x**2 + (1344 - 2688I)*x + 3840)

The pole location

z0 = Rational(205, 69) * I

The function inside the integral (without the denominator)

f = P * exp(I*x)

For a pole of order 8, we need the 7th derivative

Residue = (1/7!) * d^7/dz^7 [P(z)*e^(iz)] evaluated at z = z0

Compute the 7th derivative

f_7th_deriv = sp.diff(f, x, 7)

Evaluate at z0

residue_times_7fact = f_7th_deriv.subs(x, z0)

The residue

residue = residue_times_7fact / factorial(7)

The integral by residue theorem

I_integral = 2 * pi * I * residue

Simplify

I_integral_simplified = sp.simplify(I_integral)

print("Residue (times 7!):", residue_times_7fact) print("Residue:", residue) print("Integral I:", I_integral_simplified)

Get numerical value

I_numerical = complex(I_integral_simplified.evalf()) print("Numerical value:", I_numerical)

a = I_numerical.real b = I_numerical.imag print("a =", a) print("b =", b) print("floor(10a) =", int(sp.floor(10a))) print("floor(b) =", int(sp.floor(b))) print("Answer:", int(sp.floor(10a)) + int(sp.floor(b))) [/PYTHON]

Tool Output
[PYTHON OUTPUT] Residue (times 7!): (-337538323055683148/107918163081 - 10610677000*I*(8 + 7*I)/109503 + 4200*I*(48 - 1025*I*(17 - 12*I)/69 - 47685197*I/328509) - I*(-74925677120/7555707 - 768867260*I*(1 - 2*I)/109503 + 45067659996932375*I/7446353252589 + 1810253140625*I*(17 - 12*I)/1564031349) + 1607200*I*(1 + 3*I)/69 - 42*I*(-6427760/529 - 86100*I*(1 - 2*I)/23 + 1073421072815*I/521343783 + 430756250*I*(17 - 12*I)/328509) + 8414961427012*I/7555707)*exp(-205/69) Residue: (-337538323055683148/107918163081 - 10610677000*I*(8 + 7*I)/109503 + 4200*I*(48 - 1025*I*(17 - 12*I)/69 - 47685197*I/328509) - I*(-74925677120/7555707 - 768867260*I*(1 - 2*I)/109503 + 45067659996932375*I/7446353252589 + 1810253140625*I*(17 - 12*I)/1564031349) + 1607200*I*(1 + 3*I)/69 - 42*I*(-6427760/529 - 86100*I*(1 - 2*I)/23 + 1073421072815*I/521343783 + 430756250*I*(17 - 12*I)/328509) + 8414961427012*I/7555707)*exp(-205/69)/5040 Integral I: pi*(-43995614709051274 + 42999653639106551*I)*(1 - 2*I)*exp(-205/69)/9382405098262140 Numerical value: (0.7208218847574711+2.24792368089716j) a = 0.7208218847574711 b = 2.24792368089716 floor(10a) = 7 floor(b) = 2 Answer: 9 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python calculation gives us the integral value I=a+biI = a + bi where a0.7208a \approx 0.7208 and b2.2479b \approx 2.2479.

Therefore:

  • 10a=7.208...=7\lfloor 10a \rfloor = \lfloor 7.208... \rfloor = 7
  • b=2.247...=2\lfloor b \rfloor = \lfloor 2.247... \rfloor = 2

The answer is 7+2=97 + 2 = 9. [/THOUGHT]

\boxed{9}

Final Model Output
9

Comparative Analysis (P1) (Average across runs)

Avg Time Taken

Gemini-3-Pro-Preview
178.5
Deepseek-V3.2
61.4
Grok-4.1-fast
44.2
Claude-Opus-4.5
19.8
GPT-5.1 (high)
14.5

Avg Token Usage

Gemini-3-Pro-Preview
32384.0
Grok-4.1-fast
10096.3
Deepseek-V3.2
6802.0
Claude-Opus-4.5
4402.7
GPT-5.1 (high)
3839.3