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JNTU B.Tech II Year I Semester MATHEMATICS-IV Previous Question Paper (April/May - 2018 - R16)

B.Tech | II Year I Semester | II-I | R16 | April/May - 2018

Answer PaperPaper Code: 133BDMaximum Marks: 75Time: 3 Hours

Note: This question paper contains two parts A and B. Part A is compulsory. Part B consists of 5 Units. Answer any one full question from each unit.

Part A

125 marks
a

Show that

u = x/(x²+y²)
is harmonic.

2 marks

Answer

A function is harmonic if it satisfies Laplace's equation:

uₓₓ + uᵧᵧ = 0
. Given
u = x / (x² + y²)
:

  • uₓ = (y² - x²) / (x² + y²)²
  • uₓₓ = (2x³ - 6xy²) / (x² + y²)³
  • uᵧ = -2xy / (x² + y²)²
  • uᵧᵧ = (6xy² - 2x³) / (x² + y²)³

Summing these,

uₓₓ + uᵧᵧ = 0
, hence it is harmonic.

b

Write Cauchy-Riemann equations in polar form.

3 marks

Answer

For a complex function

f(z) = u(r,θ) + iv(r,θ)
, the Cauchy-Riemann equations in polar coordinates are:

uᵣ = (1/r) v_θ
vᵣ = -(1/r) u_θ
c

Expand

f(z) = sin z
in Taylor’s series about
z = π/4
.

2 marks

Answer

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d

Find residue of

f(z) = z/(z²+1)
at its poles.

3 marks

Answer

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e

Find image of the circle

|z| = 2
under the transformation
w = z + 3 + 2i
.

2 marks

Answer

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f

Determine the region of w-plane into which the region is mapped by the transformation

w = z²
,
|z-1| = 2
.

3 marks

Answer

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g

Find the value

bₙ
of the Fourier series of the function
f(x) = x²-2
, when
-2 ≤ x ≤ 2
.

2 marks

Answer

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h

Find the Fourier sine transformation of

2e⁻⁵ˣ + 5e⁻²ˣ
.

3 marks

Answer

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i

Classify the equation

3(∂²u/∂x²) + 6(∂²u/∂x²) + 4(∂²u/∂x∂y) - 2(∂u/∂x) + (∂u/∂y) - 4 = 0
.

2 marks

Answer

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j

Write the one dimensional Heat equation in steady state.

3 marks

Answer

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Unit I

210 marks
a

Discuss the continuity of f(x,y) = (xy)/(x²+y²) at (0,0)

5 marks

Answer

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b

Construct the analytic function f(z), whose real part is eˣcos y.

5 marks

Answer

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OR
310 marks
a

If f(z) = u+iv is an analytic function and u-v = eˣ(cos y - sin y), find f(z) in terms of z.

5 marks

Answer

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b

If u and v are harmonic, prove (∂u/∂y - ∂v/∂x) + i(∂u/∂x + ∂v/∂y) is analytic.

5 marks

Answer

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Unit II

410 marks
a

Evaluate integral of (x-y)dx - (x+y)dy over the first quadrant of x²+y²=4.

5 marks

Answer

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b

Evaluate integral dz/(z²+1) where C is |z|=2.

5 marks

Answer

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OR
510 marks
a

Obtain the expansion for sin(1/(z-1)) valid in 1 < |z| < infinity.

5 marks

Answer

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b

Evaluate integral dz/(z²(z²+8z+3)) over unit circle C.

5 marks

Answer

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Unit III

6

Prove that integral (0 to 2π) sin²θ / (a + b cos θ) dθ = (2π/b²)(a - sqrt(a²-b²)) for a > b > 0.

10 marks

Answer

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OR
7

Find the bilinear transformation that maps the points 1, i, -1 into 2, i, -2 respectively.

10 marks

Answer

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Unit IV

810 marks
a

Obtain the Fourier series for f(x) = sin x in (-π, π).

5 marks

Answer

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b

Find Fourier sine transform of e⁻ˣ and evaluate integral sin(αx)/(1+x²) dx.

5 marks

Answer

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OR
910 marks
a

Find the Half range cosine series for f(x) = x(2-x) in 0 ≤ x ≤ 2.

5 marks

Answer

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b

Find the inverse Fourier sine transform of F(p) = e⁻ᵃᵖ/p.

5 marks

Answer

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Unit V

10

Solve the heat equation ∂u/∂t = α²(∂²u/∂x²) for a rod with conditions: u bounded at t → ∞, ∂u/∂x=0 at x=0,l and u=lx-x² at t=0.

10 marks

Answer

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OR
1110 marks
a

Solve by separation of variables: ∂²z/∂x² - 2(∂z/∂x) + ∂z/∂y = 0.

5 marks

Answer

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b

Solve 4(∂u/∂x) + ∂u/∂y = 3u, given u = 3e⁻ʸ - e⁻⁵ʸ when x=0.

5 marks

Answer

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This page contains the solved question paper with answers of MATHEMATICS-IV from JNTU for B.Tech CEE II Year I Semester II-I, April/May - 2018, R16.

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