Q01. If (1 + i tanα)1+itanβ has real values only, then one of them is given by:
A 2 sec (sec) α β
B sec (sec) β α
C 2 sec (sec) β α
D None of these
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Correct answer: 2 sec (sec) β α
Q02. If r r r Z cos isin, 2 2 then Z1.Z2.Z3....∞ ∞ ∞ is equal to:
A –1
B 1
C – 1 2
D 1/2
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Correct answer: –1
Q03. The value of 2 2 cosh z sinh z − −:
A cosh(2z)
B 1
C sinh(2z)
D 0
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Correct answer: 1
Q04. The Real part of sin (x+iy) is:
A sin x
B cos y
C sin x cos hy
D sin x sin hy
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Correct answer: sin x cos hy
Q05. Time period of sin hx:
A 2πi
B –2πi
C 2π
D None of these
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Correct answer: 2πi
English Bihar (TRE 1.0) -2023
Q06. The function f (z) = |z|2 is
A continuous at the origin only
B continuous everywhere but nowhere differentiable
C continuous everywhere but nowhere differentiable, except at the origin
D More than one of the above
E None of the above
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Correct answer: continuous everywhere but nowhere differentiable, except at the origin
Q07. The analytic function whose real part is ex cosy is:
A ze2z/+ ci
B zez/+ ci
C e2z/+ ci
D ez/+ ci
Show answer
Correct answer: ez/+ ci
Q08. Match the following: Series Radius of convergence (i) n n 0 nz ∞ = ∑
A (i) - (c), (ii) - (a), (iii) - (b)
B (i) - (b), (ii) - (c), (iii) - (a)
C (i) - (b), (ii) - (a), (iii) - (c)
D (i) - (a), (ii) - (c), (iii) - (b)
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Correct answer: (i) - (b), (ii) - (c), (iii) - (a)
Q09. Which of the following is not a harmonic function?
A U = x2 +y2
B u = x2 – y2
C u = sin hx cos y
D u = 1 2 2 log(x y) 2 +
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Correct answer: U = x2 +y2
Q10. Consider the series () ∞ ∑ n 2 n=1 1 z +1 which of the following true?
A The sum of the series is z2 + 1
B The sum of the series is 2 1 z
C The series converges if z 1 <
D The sum of the series is z2 – 1
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Correct answer: The sum of the series is 2 1 z
Q11. If f(z) = |z|2, then:
A f is continuous but not differentiable at 0
B f is neither continuous nor differentiable at 0
C f is continuous and differentiable at 0
D f is discontinuous at 1
Show answer
Correct answer: f is continuous and differentiable at 0
Q12. Which of the following statements is INCORRECT?
A The composite of two continuous functions is also continuous.
B Let f (x + iy) = u (x, y) + iv (x, y). If u and v both have continuous partial derivatives with respect to x and y at point (x0, y0) then f is also differentiable at point (x0, y0).
C If f is analytic at all points interior to and on a simple closed contour C, then ʃ f (z) over C= 0.
D If f is a continuous function defined on domain D, then ʃ f (z) d (z) over (z1, z2), where z1, z2 lie in D, is the same along all contours connecting z1 and z2 and lying entirely in D.
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Correct answer: Let f (x + iy) = u (x, y) + iv (x, y). If u and v both have continuous partial derivatives with respect to x and y at point (x0, y0) then f is also differentiable at point (x0, y0).
Q13. If a function f(z) defined on some domain D of the complex plane is differentiable on D, it is said to be:
A Analytic function
B Non-singular function
C Bounded function
D Harmonic function
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Correct answer: Analytic function
Q14. Let f (r cos θ+ irsin θ) = u (r, θ) + iv (r, θ). For f to be differentiable at (r, θ), Cauchy-Riemann equation states that:
A ur = –vr/r, vr = –uθ/r
B ur = –vθ/r, vr = –uθ/r
C ur = –vθ/r, vθ = –uθ/r
D Ur = –vθ/r, vr = –uθ/r
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Correct answer: ur = –vθ/r, vr = –uθ/r
Q15. Select the function f (z) from below that is analytic on the unit sphere z < 1.
A f (z) = ex.e(–iy)
B f (z) = cos (x) cosh (y) – isin (x) sinh (y)
C f (z) = 3x + i3xy
D f (z) = 2x + ixy2
Show answer
Correct answer: f (z) = cos (x) cosh (y) – isin (x) sinh (y)
Q16. The below power series expansion represents which analytic function? () () 4n+1 z / 2n! n = 0,1,2,..., z < 100 ∑
A z sin h(z)
B z sin h (z2/)
C 1/z2
D z cos h (z2/)
Show answer
Correct answer: z cos h (z2/)
Q17. The below Taylor series expansion represents which analytic function? ∑ (–1)n z2n + 1 /(2n + 1)! (n = 0, 1, 2,.......)
A Tan z
B Sin z
C Cos hz
D Cos z
Show answer
Correct answer: Sin z
Q18. Complex valued function 2 f(z) z, for complex z, is analytic:
A Nowhere in complex plane
B At z = 0 only
C In entire complex plane
D In complex plane except at z = 0
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Correct answer: At z = 0 only
Q19. For analytic f(z) = u + iv, Cauchy-Riemann equations in polar coordinates are given by:
A r r u v,u v
B r r rv u,v ru
C r r u v,u v
D r r ru v,u rv
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Correct answer: r r ru v,u rv
Q20. The complex valued function f(z) = u(x,y) + iv(x,y), for z = x + iy, is analytic if and only if:
A v is derivative of u
B v is integral of u
C u and v are harmonic
D v is harmonic conjugate of u
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Correct answer: u and v are harmonic