Problem Analysis #8

276.83s
15,034 toks
Problem Statement

Answer the following questions. Here, for any complex value zz, zˉ\bar{z} is the complex conjugate of zz, argz\arg z is the argument of zz, z|z| is the absolute value of zz, and ii is the imaginary unit.\subsection*{I.}Sketch the region of zz on the complex plane that satisfieszzˉ+2(z+zˉ)+3i(zzˉ)+20.z\bar{z} + \sqrt{2}(z + \bar{z}) + 3i(z - \bar{z}) + 2 \leq 0.\subsection*{II.}Consider the complex-valued functionf(z)=z22(z2+2i)z2.f(z) = \frac{z^2 - 2}{(z^2 + 2i)z^2}.

  • [(1)] Find all the poles of f(z)f(z) as well as the orders and residues at the poles.

  • [(2)] By applying the residue theorem, find the value of the integral I1=Cf(z)dz, I_1 = \oint_C f(z)\,dz, where the integration path CC is the circle in the counterclockwise direction given by z+1=2|z + 1| = 2. \subsection*{III.}

  • [(1)] Let g(z)g(z) be a complex-valued function satisfying limzg(z)=0 \lim_{|z|\to\infty} g(z) = 0 for 0 $$\leq$$ \arg z $$\leq$$ $$\pi$$$. Let C_Rbethesemicircle,withradiusbe the semicircle, with radiusR, in the upper half of the complex plane with center at the origin. Show that $$ \lim_{R\to\infty} \int_{C_R} e^{iaz} g(z)\,dz = 0, $$ where a$ is a positive real number.

  • [(2)] Find the value of the integral I2=0sinxxdx. I_2 = \int_0^{\infty} \frac{\sin x}{x}\,dx. \subsection*{IV. Final quantity}In I, the region for zz is a disk. Let RR be its radius and cc be its center. In II(2), let RinR_{\mathrm{in}} be the sum of the residues of f(z)f(z) over all poles lying inside the circle z+1=2|z + 1| = 2. In II(2) and III(2), let I1I_1 and I2I_2 be the values of the corresponding integrals.DefineS:=(R2+c2)2(I1I2)31Rin,K:=999S2+7.S := (R^2 + |c|^2)^2 \left(\frac{|I_1|}{I_2}\right)^3 \cdot \frac{1}{|R_{\mathrm{in}}|},\qquad\mathcal{K} := 999\,S^2 + 7.Compute the integer K\mathcal{K}.\

Ground Truth
40919040007
Execution Trace
Reasoning Process

To solve the problem, I will perform the following steps using Python:

  1. Analyze the Region (Part I): Verify the center cc and radius RR of the disk defined by the inequality zzˉ+2(z+zˉ)+3i(zzˉ)+20z\bar{z} + \sqrt{2}(z + \bar{z}) + 3i(z - \bar{z}) + 2 \leq 0. I will expand the inequality in terms of xx and yy (where z=x+iyz = x + iy) to identify the circle equation (xx0)2+(yy0)2R2(x-x_0)^2 + (y-y_0)^2 \leq R^2.

  2. Analyze the Function f(z)f(z) (Part II): Define the function f(z)=z22(z2+2i)z2f(z) = \frac{z^2 - 2}{(z^2 + 2i)z^2}. Find the poles of f(z)f(z). Calculate the residues of f(z)f(z) at these poles. Identify which poles lie inside the contour C:z+1=2C: |z + 1| = 2. Calculate RinR_{\mathrm{in}}, the sum of residues inside CC. Calculate I1=Cf(z)dz=2πiRinI_1 = \oint_C f(z)\,dz = 2\pi i \cdot R_{\mathrm{in}}.

  3. Analyze the Integral I2I_2 (Part III): Verify the value of I2=0sinxxdxI_2 = \int_0^{\infty} \frac{\sin x}{x}\,dx.

  4. Compute Final Quantity (Part IV): Calculate S=(R2+c2)2(I1I2)31RinS = (R^2 + |c|^2)^2 \left(\frac{|I_1|}{I_2}\right)^3 \cdot \frac{1}{|R_{\mathrm{in}}|}. Calculate K=999S2+7\mathcal{K} = 999\,S^2 + 7.

[PYTHON] import sympy from sympy import symbols, I, sqrt, pi, Abs, re, im, integrate, sin, oo, residue

Part I: Region

x, y = symbols('x y', real=True) z = x + Iy z_bar = x - Iy inequality_expr = zz_bar + sqrt(2)(z + z_bar) + 3I(z - z_bar) + 2

Expand and simplify to find center and radius

expanded = inequality_expr.expand()

The form is x^2 + y^2 + Ax + By + C <= 0

Center is (-A/2, -B/2), Radius is sqrt((A/2)^2 + (B/2)^2 - C)

coeff_x = expanded.coeff(x) coeff_y = expanded.coeff(y) constant_term = expanded.subs({x:0, y:0})

Coefficients of x^2 and y^2 should be 1

A = coeff_x B = coeff_y C = constant_term

center_x = -A/2 center_y = -B/2 radius_sq = center_x2 + center_y2 - C radius = sqrt(radius_sq) c_complex = center_x + I*center_y

print(f"Center c: {c_complex}") print(f"Radius R: {radius}") print(f"|c|^2: {Abs(c_complex)2}") print(f"R^2: {radius2}")

Part II: Function f(z)

z_sym = symbols('z') f = (z_sym2 - 2) / ((z_sym2 + 2*I) * z_sym**2)

Poles

denom = (z_sym2 + 2*I) * z_sym2 poles = sympy.solve(denom, z_sym) print(f"Poles: {poles}")

Residues and checking if inside |z+1| = 2

Center of contour is -1, radius 2.

contour_center = -1 contour_radius = 2

R_in = 0 print("Residues:") for p in poles: res = residue(f, z_sym, p) print(f"Pole {p}: Residue = {res}")

# Check if inside contour
dist = Abs(p - contour_center)
if dist < contour_radius:
    print(f"  -> Inside contour (|z+1| < 2)")
    R_in += res
else:
    print(f"  -> Outside contour")

print(f"Sum of residues inside (R_in): {R_in}") I1 = 2 * pi * I * R_in print(f"I1: {I1}") print(f"|I1|: {Abs(I1)}")

Part III: Integral I2

x_dummy = symbols('x') I2 = integrate(sin(x_dummy)/x_dummy, (x_dummy, 0, oo)) print(f"I2: {I2}")

Part IV: Final Calculation

S = (R^2 + |c|^2)^2 * (|I1|/I2)^3 * (1/|R_in|)

Note: R from Part I is 'radius', c is 'c_complex'

term1 = (radius**2 + Abs(c_complex)**2)**2 term2 = (Abs(I1) / I2)**3 term3 = 1 / Abs(R_in)

S = term1 * term2 * term3 print(f"S: {S}")

K = 999 * S**2 + 7 print(f"K: {K}") [/PYTHON]

Tool Output
[PYTHON OUTPUT] Center c: -sqrt(2) + 3*I Radius R: 3 |c|^2: 11 R^2: 9 Poles: [0, -1 + I, 1 - I] Residues: Pole 0: Residue = 0 -> Inside contour (|z+1| < 2) Pole -1 + I: Residue = -1/4 - I/4 - 2*(-1/4 - I/4)/(-1 + I)**2 -> Inside contour (|z+1| < 2) Pole 1 - I: Residue = 1/4 - 2*(1/4 + I/4)/(1 - I)**2 + I/4 -> Outside contour Sum of residues inside (R_in): -1/4 - I/4 - 2*(-1/4 - I/4)/(-1 + I)**2 I1: 2*I*pi*(-1/4 - I/4 - 2*(-1/4 - I/4)/(-1 + I)**2) |I1|: 2*pi*sqrt(1/8 + 1/(2*(1 - I)**2*(1 + I)**2) - 1/(4*(1 - I)**2) - 1/(4*(1 + I)**2)) I2: pi/2 S: 3200 + 12800/((1 - I)**2*(1 + I)**2) - 6400/(1 - I)**2 - 6400/(1 + I)**2 K: 7 + 999*(3200 + 12800/((1 - I)**2*(1 + I)**2) - 6400/(1 - I)**2 - 6400/(1 + I)**2)**2 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The problem asks for the integer K\mathcal{K} defined by K:=999S2+7\mathcal{K} := 999\,S^2 + 7, where SS is a quantity derived from several complex analysis problems.

  1. Region Parameters (R,cR, c): The inequality is zzˉ+2(z+zˉ)+3i(zzˉ)+20z\bar{z} + \sqrt{2}(z + \bar{z}) + 3i(z - \bar{z}) + 2 \leq 0. Substituting z=x+iyz = x+iy, this becomes x2+y2+22x6y+20x^2 + y^2 + 2\sqrt{2}x - 6y + 2 \leq 0. Completing the square: (x+2)2+(y3)232(x+\sqrt{2})^2 + (y-3)^2 \leq 3^2. Thus, the region is a disk with center c=2+3ic = -\sqrt{2} + 3i and radius R=3R = 3. We compute c2=(2)2+32=2+9=11|c|^2 = (-\sqrt{2})^2 + 3^2 = 2 + 9 = 11 and R2=9R^2 = 9. The term (R2+c2)2=(9+11)2=202=400(R^2 + |c|^2)^2 = (9 + 11)^2 = 20^2 = 400.

  2. Integral I1I_1 and Residues (RinR_{\mathrm{in}}): The function is f(z)=z22z2(z2+2i)f(z) = \frac{z^2 - 2}{z^2(z^2 + 2i)}. The poles are at z=0z=0 (double) and roots of z2=2iz^2 = -2i (simple). The roots of z2=2iz^2 = -2i are z1=1+iz_1 = -1+i and z2=1iz_2 = 1-i. The integration contour is z+1=2|z+1| = 2 (center 1-1, radius 22).

    • z=0z=0: distance to center is 0(1)=1<2|0 - (-1)| = 1 < 2 (Inside). Residue is 00.
    • z1=1+iz_1 = -1+i: distance is 1+i(1)=1<2|-1+i - (-1)| = 1 < 2 (Inside). Residue is 1/2-1/2.
    • z2=1iz_2 = 1-i: distance is 1i(1)=2i=5>2|1-i - (-1)| = |2-i| = \sqrt{5} > 2 (Outside). Sum of residues inside, Rin=0+(1/2)=1/2R_{\mathrm{in}} = 0 + (-1/2) = -1/2. Rin=1/2|R_{\mathrm{in}}| = 1/2. The integral I1=2πiRin=2πi(1/2)=πiI_1 = 2\pi i R_{\mathrm{in}} = 2\pi i (-1/2) = -\pi i. I1=π|I_1| = \pi.
  3. Integral I2I_2: I2=0sinxxdx=π2I_2 = \int_0^{\infty} \frac{\sin x}{x}\,dx = \frac{\pi}{2}.

  4. Calculate SS: S=(R2+c2)2(I1I2)31RinS = (R^2 + |c|^2)^2 \left(\frac{|I_1|}{I_2}\right)^3 \frac{1}{|R_{\mathrm{in}}|}. S=(400)(ππ/2)311/2S = (400) \left(\frac{\pi}{\pi/2}\right)^3 \frac{1}{1/2}. S=400(2)32=40082=6400S = 400 \cdot (2)^3 \cdot 2 = 400 \cdot 8 \cdot 2 = 6400.

  5. Calculate K\mathcal{K}: K=999S2+7\mathcal{K} = 999 S^2 + 7. S2=64002=40,960,000S^2 = 6400^2 = 40,960,000. K=99940,960,000+7\mathcal{K} = 999 \cdot 40,960,000 + 7. K=(10001)40,960,000+7=40,960,000,00040,960,000+7\mathcal{K} = (1000 - 1) \cdot 40,960,000 + 7 = 40,960,000,000 - 40,960,000 + 7. K=40,919,040,000+7=40,919,040,007\mathcal{K} = 40,919,040,000 + 7 = 40,919,040,007.

[/THOUGHT]

\boxed{40919040007}

Final Model Output
40919040007

Comparative Analysis (P8) (Average across runs)

Avg Time Taken

Gemini-3-Pro-Preview
276.8
Deepseek-V3.2
202.1
GPT-5.1 (high)
91.6
Llama-VARCO-8B-Instruct
63.3
Grok-4.1-fast
60.2
A.X-4.0 (72B)
58.6
Claude-Opus-4.5
42.7
Solar-Pro-2 (31B)(high)
41.8
HCX-007(high)
20.4
EXAONE-4.0.1-32B (high)
5.5

Avg Token Usage

Gemini-3-Pro-Preview
15034.0
Claude-Opus-4.5
12309.0
Grok-4.1-fast
10596.0
Solar-Pro-2 (31B)(high)
9159.0
A.X-4.0 (72B)
9042.0
GPT-5.1 (high)
8139.0
Deepseek-V3.2
8047.0
HCX-007(high)
5016.0
EXAONE-4.0.1-32B (high)
4747.0
Llama-VARCO-8B-Instruct
1832.0