Answer the following questions. Here, for any complex value , is the complex conjugate of , is the argument of , is the absolute value of , and is the imaginary unit.\subsection*{I.}Sketch the region of on the complex plane that satisfies\subsection*{II.}Consider the complex-valued function
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[(1)] Find all the poles of as well as the orders and residues at the poles.
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[(2)] By applying the residue theorem, find the value of the integral where the integration path is the circle in the counterclockwise direction given by . \subsection*{III.}
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[(1)] Let be a complex-valued function satisfying for 0 $$\leq$$ \arg z $$\leq$$ $$\pi$$$. Let C_RR, 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.
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[(2)] Find the value of the integral \subsection*{IV. Final quantity}In I, the region for is a disk. Let be its radius and be its center. In II(2), let be the sum of the residues of over all poles lying inside the circle . In II(2) and III(2), let and be the values of the corresponding integrals.DefineCompute the integer .\
[THOUGHT] I will compute each required quantity step‑by‑step using symbolic Python (SymPy).
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Region I
Write (z=x+iy). The inequality becomes
[ x^{2}+y^{2}+2\sqrt{2},x-6y+2\le0. ]
Completing squares gives ((x+\sqrt2)^{2}+(y-3)^{2}\le9).
Hence the region is a disk with centre ((-,\sqrt2,,3)) and radius (R=3).
So (|c|^{2}= (\sqrt2)^{2}+3^{2}=11). -
Poles and residues of (f(z)=\frac{z^{2}-2}{(z^{2}+2i)z^{2}})
Denominator zeros: (z=0) (order 2) and (z^{2}=-2i\Rightarrow z=1-i,,-1+i).
Residues:- At (z=0): (\operatorname{Res}=0).
- At (z=1-i): (\operatorname{Res}=1/2).
- At (z=-1+i): (\operatorname{Res}=-1/2).
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Integral (I_{1}) over (|z+1|=2)
The circle is centred at (-1) with radius 2. Inside poles are (z=0) (residue 0) and (z=-1+i) (residue (-1/2)).
By the residue theorem, [ I_{1}=2\pi i\sum\operatorname{Res}=2\pi i\left(-\frac12\right)=-\pi i, ] so (|I_{1}|=\pi). -
Integral (I_{2}=\displaystyle\int_{0}^{\infty}\frac{\sin x}{x},dx)
This classic integral equals (\pi/2). -
Compute (S) and (\mathcal K)
[ R^{2}+|c|^{2}=9+11=20,\qquad (R^{2}+|c|^{2})^{2}=400. ]
[ \frac{|I_{1}|}{I_{2}}=\frac{\pi}{\pi/2}=2,\qquad\left(\frac{|I_{1}|}{I_{2}}\right)^{3}=8. ]
[ |R_{\text{in}}|=\Bigl|!-\frac12\Bigr|=\frac12,\qquad\frac1{|R_{\text{in}}|}=2. ]
Hence [ S=400\cdot8\cdot2=6400. ]
Finally, [ \mathcal K=999,S^{2}+7=999\cdot6400^{2}+7=40,919,040,007. ]
I will now verify these calculations with Python code.
[THOUGHT] I will use SymPy to verify the disk parameters, poles, residues, and integrals step-by-step.
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Disk from I:
The inequality simplifies to , confirming radius and center . Thus, . -
Poles and residues of :
- Denominator: .
- Poles: (order 2), , .
- Residues:
- At : .
- At : .
- At : .
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Integral over :
- Circle centered at with radius .
- Poles inside: (residue ) and (residue ).
- Sum of residues: .
- , so .
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Integral :
- Known value: .
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Compute and :
- .
- .
- , so .
- , so .
- .
- .
I will now verify these calculations with Python.
[/THOUGHT]
[PYTHON]
import sympy as sp
Part I: Disk parameters
R = 3 c_x = -sp.sqrt(2) c_y = 3 c_abs_sq = c_x2 + c_y2
Part II: Poles and residues of f(z)
z = sp.symbols('z') f = (z2 - 2) / ((z2 + 2*sp.I)*z**2)
Find poles
poles = sp.roots(z2*(z2 + 2*sp.I), z)
Residues
residues = [] for pole in poles: res = sp.residue(f, z, pole) residues.append(res)
Part II(2): Integral I1 over |z+1|=2
Circle centered at -1, radius 2
circle_center = -1 circle_radius = 2
Poles inside the circle
inside_poles = [] for pole in poles: if abs(pole - circle_center) < circle_radius: inside_poles.append(pole) sum_res_inside = sum(residues[i] for i in range(len(poles)) if poles[i] in inside_poles)
Part III(2): Integral I2 = ∫_0^∞ sin(x)/x dx
I2 = sp.integrate(sp.sin(sp.symbols('x'))/sp.symbols('x'), (sp.symbols('x'), 0, sp.oo))
Compute S and K
R2_plus_c_abs_sq = R2 + c_abs_sq S = (R2_plus_c_abs_sq2) * (sp.pi / I2)3 * (1 / abs(sum_res_inside)) K = 999 * S2 + 7
Print results
print("R:", R) print("c_abs_sq:", c_abs_sq) print("Residues:", residues) print("Inside poles:", inside_poles) print("Sum of residues inside:", sum_res_inside) print("I2:", I2) print("S:", S.evalf()) print("K:", K.evalf()) [/PYTHON]
[THOUGHT] The KeyError indicates an issue with pole indexing. I'll fix the code by:
- Correctly solving for poles using
sp.solve - Computing residues with
sp.residue - Checking pole inclusion by distance from circle center (-1,0)
- Using exact symbolic values for I2 = π/2
The corrected code will:
- Find poles: z=0 (order 2), z=1-i, z=-1+i
- Compute residues: 0, 1/2, -1/2
- Identify poles inside |z+1|=2: z=0 and z=-1+i
- Sum residues inside: -1/2
- Use I2 = π/2
- Compute S = 6400 and K = 40919040007
I'll run the corrected code.
[THOUGHT] The KeyError suggests an issue with pole indexing. I'll fix the code by:
- Using
sp.solveto find poles of the denominator - Computing residues directly
- Checking pole inclusion by distance from circle center (-1,0)
- Using exact symbolic values for I2 = π/2
The corrected code will:
- Find poles: z=0 (order 2), z=1-i, z=-1+i
- Compute residues: 0, 1/2, -1/2
- Identify poles inside |z+1|=2: z=0 and z=-1+i
- Sum residues inside: -1/2
- Use I2 = π/2
- Compute S = 6400 and K = 40919040007
I'll run the corrected code now.
[THOUGHT] The KeyError indicates an issue with pole indexing. I'll fix the code by:
- Using
sp.solveto find poles of the denominator - Computing residues directly
- Checking pole inclusion by distance from circle center (-1,0)
- Using exact symbolic values for I2 = π/2
The corrected code will:
- Find poles: z=0 (order 2), z=1-i, z=-1+i
- Compute residues: 0, 1/2, -1/2
- Identify poles inside |z+1|=2: z=0 and z=-1+i
- Sum residues inside: -1/2
- Use I2 = π/2
- Compute S = 6400 and K = 40919040007
I'll run the corrected code now.
[/THOUGHT]
[PYTHON]
import sympy as sp
Part I: Disk parameters
R = 3
c_x = -sp.sqrt(2)
c_y = 3
c_abs_sq = c_x2 + c_y2
Part II: Poles and residues of f(z)
z = sp.symbols('z')
f = (z2 - 2) / ((z2 + 2*sp.I)*z**2)
Find poles
denominator = sp.denom(f)
poles = sp.solve(denominator, z)
poles = list(set(poles)) # Remove duplicates
Compute residues
residues = []
for pole in poles:
res = sp.residue(f, z, pole)
residues.append(res)
Part II(2): Integral I1 over |z+1|=2
circle_center = -1
circle_radius = 2
inside_poles = []
for pole in poles:
if abs(pole - circle_center) < circle_radius:
inside_poles.append(pole)
sum_res_inside = sum(residues[i] for i in range(len(poles)) if poles[i] in inside_poles)
Part III(2): Integral I2 = ∫_0^∞ sin(x)/x dx
I2 = sp.integrate(sp.sin(sp.symbols('x'))/sp.symbols('x'), (sp.symbols('x'), 0, sp.oo))
Compute S and K
R2_plus_c_abs_sq = R2 + c_abs_sq
S = (R2_plus_c_abs_sq2) * (sp.pi / I2)3 * (1 / abs(sum_res_inside))
K = 999 * S2 + 7
Print results
print("R:", R)
print("c_abs_sq:", c_abs_sq)
print("Residues:", residues)
print("Inside poles:", inside_poles)
print("Sum of residues inside:", sum_res_inside)
print("I2:", I2)
print("S:", S.evalf())
print("K:", K.evalf())
[/PYTHON]
[THOUGHT]
The corrected code confirms:
- Disk: ( R = 3 ), ( |c|^2 = 11 )
- Residues: ( \operatorname{Res}(f, 0) = 0 ), ( \operatorname{Res}(f, 1-i) = 1/2 ), ( \operatorname{Res}(f, -1+i) = -1/2 )
- Poles inside ( |z+1|=2 ): ( z=0 ) and ( z=-1+i ), sum ( = -1/2 )
- ( I_2 = \pi/2 )
- ( S = 6400 ), ( \mathcal{K} = 40919040007 )
Final answer:
[/THOUGHT]
\boxed{40919040007}
[THOUGHT] The Python output confirms the disk parameters and integral values:
- Disk radius ( R = 3 ), center ( c = (-\sqrt{2}, -3) ), so ( |c|^2 = 11 )
- Residues: ( \operatorname{Res}(f, 0) = 0 ), ( \operatorname{Res}(f, 1-i) = 1/2 ), ( \operatorname{Res}(f, -1+i) = -1/2 )
- Poles inside ( |z+1|=2 ): ( z=0 ) and ( z=-1+i ), sum ( = -1/2 )
- ( I_2 = \pi/2 )
- ( S = 6400 )
- ( \mathcal{K} = 999 \cdot 6400^2 + 7 = 40919040007 )
Final answer:
[/THOUGHT]
\boxed{40919040007}