Problem Analysis #2

39.02s
7,089 toks
Problem Statement

Let aa, bb, cc be natural numbers satisfying

{a+b+c=151a2+b2+c2=10939a3+b3+c3=957871\begin{cases} a + b + c = 151 \\ a^{2} + b^{2} + c^{2} = 10939 \\ a^{3} + b^{3} + c^{3} = 957871 \end{cases}

Let

Q(x)=(xa)(xb)(xc).Q(x)=(x-a)(x-b)(x-c).

Evaluate

I=Q(x)eix(x20569i)4dx.I = \int_{-\infty}^{\infty} \frac{Q(x)e^{ix}}{\left(x-\frac{205}{69}i\right)^{4}}\,dx.

If I=α+βiI=\alpha+\beta i, compute 10α+β\lfloor 10\alpha \rfloor + \lfloor \beta \rfloor.

Ground Truth
-36330
Execution Trace
Reasoning Process

The problem asks us to evaluate an integral II involving a polynomial Q(x)Q(x) determined by the roots a,b,ca, b, c, which satisfy a system of power sums.

First, we determine the coefficients of the polynomial Q(x)=(xa)(xb)(xc)=x3e1x2+e2xe3Q(x) = (x-a)(x-b)(x-c) = x^3 - e_1 x^2 + e_2 x - e_3. Using Newton sums: e1=p1=151e_1 = p_1 = 151 e2=e1p1p22e_2 = \frac{e_1 p_1 - p_2}{2} e3=e2p1e1p2+p33e_3 = \frac{e_2 p_1 - e_1 p_2 + p_3}{3}

Then we evaluate the integral I=Q(x)eix(xz0)4dxI = \int_{-\infty}^{\infty} \frac{Q(x)e^{ix}}{(x-z_0)^4} dx using the residue theorem, where z0=20569iz_0 = \frac{205}{69}i. Since z0z_0 is in the upper half-plane, the integral is 2πiRes(f,z0)2\pi i \cdot \text{Res}(f, z_0). The residue for a pole of order 4 is 16d3dz3[Q(z)eiz]z=z0\frac{1}{6} \frac{d^3}{dz^3} [Q(z)e^{iz}] \bigg|_{z=z_0}.

Let's perform the calculations.

[PYTHON] import cmath

Given power sums

p1 = 151 p2 = 10939 p3 = 957871

Calculate elementary symmetric polynomials

e1 = p1 e2 = (e1 * p1 - p2) // 2 e3 = (e2 * p1 - e1 * p2 + p3) // 3

print(f"{e1=}, {e2=}, {e3=}")

Define Q and its derivatives at a point z

Q(z) = z^3 - e1z^2 + e2z - e3

def get_Q_derivs(z): # Q(z) Q0 = z3 - e1*z2 + e2z - e3 # Q'(z) = 3z^2 - 2e1z + e2 Q1 = 3z**2 - 2e1z + e2 # Q''(z) = 6z - 2e1 Q2 = 6z - 2*e1 # Q'''(z) = 6 Q3 = 6 return Q0, Q1, Q2, Q3

The pole z0

z0 = 205/69 * 1j

Calculate the term from the 3rd derivative of Q(z)e^{iz}

g'''(z) = [Q'''(z) + 3i Q''(z) - 3 Q'(z) - i Q(z)] e^{iz}

Q0, Q1, Q2, Q3 = get_Q_derivs(z0) term_bracket = Q3 + 3j * Q2 - 3 * Q1 - 1j * Q0 exp_term = cmath.exp(1j * z0)

Integral I = 2pii * (1/6) * term_bracket * exp_term

I = (2 * cmath.pi * 1j / 6) * term_bracket * exp_term

alpha = I.real beta = I.imag

print(f"{I=}") print(f"{alpha=}") print(f"{beta=}")

Compute final answer

ans = int(10 * alpha) + int(beta) # Using int() acts like floor for positive, but check signs import math ans_floor = math.floor(10 * alpha) + math.floor(beta) print(f"{ans_floor=}") [/PYTHON]

Tool Output
[PYTHON OUTPUT] e1=151, e2=5931, e3=67221 I=(-3632.072015780717-8.918590039262718j) alpha=-3632.072015780717 beta=-8.918590039262718 ans_floor=-36330 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python code calculated the elementary symmetric polynomials e1,e2,e3e_1, e_2, e_3 correctly from the power sums. e1=151e_1 = 151 e2=5931e_2 = 5931 e3=67221e_3 = 67221 The integral II was evaluated using the residue theorem. The pole is at z0=20569iz_0 = \frac{205}{69}i. Since the imaginary part is positive, the pole is inside the contour (assuming standard semi-circle in upper half plane). The residue calculation formula used was 13!d3dz3[Q(z)eiz]\frac{1}{3!} \frac{d^3}{dz^3} [Q(z)e^{iz}]. The code output I3632.0728.919iI \approx -3632.072 - 8.919i. α3632.072\alpha \approx -3632.072 β8.919\beta \approx -8.919 The quantity to compute is 10α+β\lfloor 10\alpha \rfloor + \lfloor \beta \rfloor. 10α36320.72    10α=3632110\alpha \approx -36320.72 \implies \lfloor 10\alpha \rfloor = -36321. β8.919    β=9\beta \approx -8.919 \implies \lfloor \beta \rfloor = -9. Sum = 36321+(9)=36330-36321 + (-9) = -36330. The code output ans_floor = -36330 confirms this. Wait, let me double check the int() vs floor() logic in the code output. The code printed ans_floor=-36330. math.floor(-36320.72) is -36321. math.floor(-8.919) is -9. Sum is -36330. The code output is consistent.

Final check on the integral formula. P(x)(xz0)n+1dx=2πi1n!dndzn[P(z)]z=z0\int_{-\infty}^\infty \frac{P(x)}{(x-z_0)^{n+1}} dx = 2\pi i \frac{1}{n!} \frac{d^n}{dz^n} [P(z)]_{z=z_0}? No. The integrand is f(x)=Q(x)eix(xz0)4f(x) = \frac{Q(x)e^{ix}}{(x-z_0)^4}. Let g(z)=Q(z)eizg(z) = Q(z)e^{iz}. The residue at z0z_0 (order 4) is 13!g(z0)\frac{1}{3!} g'''(z_0). So I=2πi16g(z0)I = 2\pi i \cdot \frac{1}{6} g'''(z_0). The code implemented exactly this. g(z)=d3dz3(Q(z)eiz)g'''(z) = \frac{d^3}{dz^3} (Q(z)e^{iz}). Using Leibniz rule or direct expansion: g(z)=Qeiz+iQeiz=(Q+iQ)eizg'(z) = Q' e^{iz} + i Q e^{iz} = (Q' + iQ) e^{iz} g(z)=(Q+iQ)eiz+i(Q+iQ)eiz=(Q+2iQQ)eizg''(z) = (Q'' + iQ') e^{iz} + i(Q' + iQ) e^{iz} = (Q'' + 2iQ' - Q) e^{iz} g(z)=(Q+2iQQ)eiz+i(Q+2iQQ)eiz=(Q+3iQ3QiQ)eizg'''(z) = (Q''' + 2iQ'' - Q') e^{iz} + i(Q'' + 2iQ' - Q) e^{iz} = (Q''' + 3iQ'' - 3Q' - iQ) e^{iz}. The code used term_bracket = Q3 + 3j * Q2 - 3 * Q1 - 1j * Q0. This matches (Q+3iQ3QiQ)(Q''' + 3iQ'' - 3Q' - iQ). The factor eiz0e^{iz_0} was included. The factor 2πi/62\pi i / 6 was included. The calculation seems correct.

One detail: z0=20569iz_0 = \frac{205}{69}i. eiz0=ei(205/69)i=e205/69e^{i z_0} = e^{i (205/69) i} = e^{-205/69}. This is a real number. Q(z)Q(z) coefficients are real. z0z_0 is purely imaginary. Let z0=kiz_0 = ki. Q(ki)=(ki)3e1(ki)2+e2(ki)e3=k3i+e1k2+e2kie3=(e1k2e3)+i(e2kk3)Q(ki) = (ki)^3 - e_1(ki)^2 + e_2(ki) - e_3 = -k^3 i + e_1 k^2 + e_2 k i - e_3 = (e_1 k^2 - e_3) + i(e_2 k - k^3). Q(ki)=3(ki)22e1(ki)+e2=3k22e1ki+e2=(e23k2)i(2e1k)Q'(ki) = 3(ki)^2 - 2e_1(ki) + e_2 = -3k^2 - 2e_1 k i + e_2 = (e_2 - 3k^2) - i(2e_1 k). Q(ki)=6ki2e1=2e1+i(6k)Q''(ki) = 6ki - 2e_1 = -2e_1 + i(6k). Q(ki)=6Q'''(ki) = 6.

Term bracket B=Q+3iQ3QiQB = Q''' + 3iQ'' - 3Q' - iQ. B=6+3i(2e1+6ki)3((e23k2)2ie1k)i((e1k2e3)+i(e2kk3))B = 6 + 3i(-2e_1 + 6ki) - 3((e_2 - 3k^2) - 2ie_1 k) - i((e_1 k^2 - e_3) + i(e_2 k - k^3)) B=66ie118k3e2+9k2+6ie1kie1k2+ie3+e2kk3B = 6 - 6ie_1 - 18k - 3e_2 + 9k^2 + 6ie_1 k - ie_1 k^2 + ie_3 + e_2 k - k^3 Real part of B: 618k3e2+9k2+e2kk36 - 18k - 3e_2 + 9k^2 + e_2 k - k^3. Imaginary part of B: 6e1+6e1ke1k2+e3-6e_1 + 6e_1 k - e_1 k^2 + e_3.

Then I=iπ3BekI = \frac{i \pi}{3} B e^{-k}. I=π3ek(iRe(B)Im(B))I = \frac{\pi}{3} e^{-k} (i \text{Re}(B) - \text{Im}(B)). So Re(I)=π3ekIm(B)\text{Re}(I) = -\frac{\pi}{3} e^{-k} \text{Im}(B). Im(I)=π3ekRe(B)\text{Im}(I) = \frac{\pi}{3} e^{-k} \text{Re}(B).

The code output: α=Re(I)3632.07\alpha = \text{Re}(I) \approx -3632.07. β=Im(I)8.92\beta = \text{Im}(I) \approx -8.92. The signs and magnitudes are handled by the code. The result ans_floor is -36330. [/THOUGHT]

\boxed{-36330}

Final Model Output
-36330

Comparative Analysis (P2) (Average across runs)

Avg Time Taken

Grok-4.1-fast
523.0
Gemini-3-Pro-Preview
230.2
Deepseek-V3.2
109.2
Claude-Opus-4.5
27.1
GPT-5.1 (high)
22.7

Avg Token Usage

Grok-4.1-fast
88291.3
Gemini-3-Pro-Preview
21876.7
Deepseek-V3.2
9837.0
Claude-Opus-4.5
8021.3
GPT-5.1 (high)
4542.7