English Bihar (TRE 1.0) -2023
Q01. For the function () -z 1-e f z = z the point z = 0 is a/an
A essential singularity
B pole of order one
C removable singularity
D More than one of the above
E None of the above
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Correct answer: removable singularity
English Bihar (TRE 1.0) -2023
Q02. Let g be any positively oriented circle whose centre is at the origin. Then the value of the integral ∫ 2 γ cosz dz z is
A 2πi
B 0
C –2πi
D More than one of the above
E None of the above
Show answer
Correct answer: 0
English Bihar (TRE 1.0) -2023
Q03. Let a-2 be the coefficient of 2 1 z in the Laurent series of f(z) = () 3 2 z +1 z z +1 around z = 0 in the region 0 < |z| < 1. Then a–2 is equal to
A 1
B 0
C –1
D More than one of the above
E None of the above
Show answer
Correct answer: 1
English Bihar (TRE 1.0) -2023
Q04. Let f: C → → → C be an entire function with f (0) = 1 and f (1) = 0. Then f maps
A open sets in C into open sets in C
B closed sets in C into closed sets in C
C open sets in C into closed sets in C
D More than one of the above
E None of the above
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Correct answer: open sets in C into open sets in C
English Bihar (TRE 1.0) -2023
Q05. A non-constant entire function
A has at least one zero in c
B cannot have finite number of real zeros
C cannot have uncountable number of zeros in C
D More than one of the above
E None of the above
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Correct answer: cannot have uncountable number of zeros in C
English Bihar (TRE 1.0) -2023
Q06. f is an entire function. If f satisfies the following two equations f (z +1) = f (z) and f (z + i) = f (z) for every z in c then
A f = constant
B f (z) ∈ R∀z
C f is a non-constant polynomial
D More than one of the above
E None of the above
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Correct answer: f = constant
Q07. The residue at z = ∞ for the function f(z) = z3 cos 1 z is:
A −1/24
B –1
C 0
D 1/12
Show answer
Correct answer: −1/24
Q08. The value of 2 c z z 1 dz, z 1 − + − ∫ where c is the circle z = 1, is:
A 0
B 2πi
C –2πi
D πi
Show answer
Correct answer: 0
Q09. Evaluation of 2 |z| 10.5 z cot zdz = π ∫ is equal to:
A 1240 i
B 220 i
C 1540 i
D 12100 i
Show answer
Correct answer: Discrepancy / answer not specified in source
Q10. A semi-circular disc with centre at origin and radius 2 unit is in Z – plane, its image in w– plane under the transformation w2 = Z is -
A circular disc of radius 2 units
B semi-circular disc of radius 2 units
C quarter circular disc of radius 2 units
D quarter circular disc of radius 4 units
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Correct answer: quarter circular disc of radius 2 units
Q11. Consider the integrals I1 = () c, ∫ z 4 e dz z +1 where c is a circle z = 2 And I2 = c, ∫ 2 sin3z dz z, where c is circle z = 1 Then:
A 1 2 ie I, I 2 i 3 π = π
B 1 2 i I, I –6 i 3e π = π
C 1 2 ie I, I 0 3 π =
D 1 2 i I, I 6 i 3e π = π
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Correct answer: 1 2 i I, I 6 i 3e π = π
Q12. Consider the bilinear transformer z –1 z 1 ω = +. Which of the following is true?
A The fixed point are z = i ± and the transformer is hyperbolic
B The fixed point are z = 1, 2 and the transformation is elliptic
C The fixed point are z = ± i and the transformation is elliptic
D The fixed point z = ± 1 and the transformation is hyperbolic
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Correct answer: The fixed point are z = ± i and the transformation is elliptic
Q13. Let T: C ∪ ∪ ∪ {∞ ∞ ∞} ⇒ ⇒ ⇒ C ∪ ∪ ∪ {∞ ∞ ∞} be the bilinear transformation such that T(i) = 0, T(0) = –1, T(–i) = ∞ ∞ ∞. Then the image of the region, {z ∈ C: I m (z) = 0} under the mapping ω = T(z) is:
A { } C: 1 ω∈ ω >
B { } C: 1 ω∈ ω <
C { } C: 1 ω∈ ω =
D () () { } C: Re 0,Im 0 ω∈ ω = ω =
Show answer
Correct answer: { } C: 1 ω∈ ω =
Q14. Let f(z) = () cos z 1, z 1 − then,
A f(z) has isolated essential singularity at z = 1
B f(z) has simple pole at z = 1
C Residue of f at z =1 is undefined
D Residue of f at z =1 is not equal to 1
Show answer
Correct answer: f(z) has simple pole at z = 1
Q15. The function f(z) = z e 2 2 1 − has
A An essential singularity at z = 0
B A pole at z = 0
C An essential singularity at z = ∞
D No singularity
Show answer
Correct answer: An essential singularity at z = 0
Q16. The residue of the function f(x) = 1 x e − at x = 0
A is 1
B Does not exist, since, 0 is not a singular point
C is 0
D Does not exist, since 0 is not a non-isolated singular point
Show answer
Correct answer: Discrepancy / answer not specified in source
Q17. Let f(z) = () 2 z +1 z z -1 then the product of the residues of f at poles is:
A 1
B 0
C 2
D –2
Show answer
Correct answer: –2
Q18. Using Residue Theorem, evaluate the integral ʃ (5z – 2)
A 6πi
B 10πi
C 5πi
D 8πi
Show answer
Correct answer: 10πi
Q19. If C is a positively oriented simple closed contour within and on which function f is analytic, except for a finite number of singular points zk (k = 1, 2,.... n) interior to C, then Residue Theorem states that:
A () () () C k k f z dz e i Resf z / k! = π ∑ ∫
B n k k 1 c f(z)dz 2 i Res[f(z);z ] = π ∑ ∫
C () () () C k k f z dz 2 i Resf z / k! = π ∑ ∫
D () () () C k k f z dz Resf z = ∑ ∫
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Correct answer: n k k 1 c f(z)dz 2 i Res[f(z);z ] = π ∑ ∫
Q20. Let C denote the boundary of circle with radius 3 around the centre z1 = 2 + i. Calculate the integral () ∫ az I = e / z – 2 – i dz over contour C.
A 0
B () a 2–i 2 i e π
C () a 2 i 2 i e + π
D () a 2 2i 2 i e + π
Show answer
Correct answer: () a 2 i 2 i e + π