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JNTU B.Tech I Year MATHEMATICS-II Previous Question Paper (December - 2017 - R16)

B.Tech | I Year | I-I | R16 | December - 2017

Answer PaperPaper Code: 131ABMaximum Marks: 75Time: 3 hours

Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b as sub questions.

Part A

1a

Find the Laplace transform of cosh3(2t).

2 marks

Answer

Using the identity cosh(3x) = 4cosh3(x) - 3cosh(x), we can express cosh3(2t) as:

cosh3(2t) = (1/4)cosh(6t) + (3/4)cosh(2t)

Applying the linearity property of the Laplace transform and the standard formula L{cosh(at)} = s / (s2 - a2), we get:

L{cosh3(2t)} = (1/4) * [s / (s2 - 62)] + (3/4) * [s / (s2 - 22)]
= s / 4 * [1 / (s2 - 36) + 3 / (s2 - 4)]
= s(s2 - 4 + 3s2 - 108) / [4(s2 - 36)(s2 - 4)]
= s(4s2 - 112) / [4(s2 - 36)(s2 - 4)]
= s(s2 - 28) / [(s2 - 36)(s2 - 4)]
1b

Find the Laplace transform of e-t(2cos 5t - 3sin 5t).

3 marks

Answer

Using the linearity property of the Laplace transform, we have:

L{e-t(2cos 5t - 3sin 5t)} = 2L{e-tcos 5t} - 3L{e-tsin 5t}

Applying the first shifting theorem, which states that L{eatf(t)} = F(s - a), where F(s) = L{f(t)}:

For f(t) = cos 5t, F(s) = s / (s2 + 25). Thus, L{e-tcos 5t} = (s + 1) / ((s + 1)2 + 25).

For f(t) = sin 5t, F(s) = 5 / (s2 + 25). Thus, L{e-tsin 5t} = 5 / ((s + 1)2 + 25).

Substituting these back into the expression:

2((s + 1) / ((s + 1)2 + 25)) - 3(5 / ((s + 1)2 + 25))
= (2s + 2 - 15) / (s2 + 2s + 1 + 25)
= (2s - 13) / (s2 + 2s + 26)
1c

Evaluate the improper integral

∫0∞ x2 e-x dx
using Gamma function.

2 marks

Answer

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1d

Evaluate the improper integral

∫01 (ln(1/x))1/2 dx
using Beta and Gamma functions.

3 marks

Answer

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1e

Find the area bounded by the curves y2 = 4ax and x2 = 4ay using double integration.

2 marks

Answer

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1f

Change the order of the integration

∫01 ∫0√(1-y2) (1/(1+x2+y2)) dxdy
and evaluate the integral.

3 marks

Answer

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1g

Find ∇φ, when φ = 3x2y - y3z2 at the point (1, -2, -1).

2 marks

Answer

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1h

Find the directional derivative of the function f(x, y, z) = xy2 + yz2 at the point (1, -1, 3) in the direction of the vector i + 2j + 2k.

3 marks

Answer

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1i

If R = (t-1)i + t2j + (t-3)k and S = 2t2i + 6tk, evaluate

∫02 R × S dt
.

2 marks

Answer

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1j

Evaluate the line integral

∮C (3x2-8y2) dx + (4y-6xy) dy
, where C is the boundary of the region y = x and y = x2.

3 marks

Answer

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Part B

210 marks
a

Find the Laplace transform of (sin t)/t. Hence find L(cos t)/t.

5 marks

Answer

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b

Prove that

∫0∞ ∫0∞ (e-ut sin t)/t dt du = π/4
.

5 marks

Answer

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OR
310 marks
a

Find the inverse Laplace transform of ln((s+1)/(s-1)).

5 marks

Answer

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b

Find the inverse Laplace transform of 1/(s2(s2+a2)) using the convolution theorem.

5 marks

Answer

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410 marks
a

Prove that

∫0∞ cos(ax)/(xn+an) dx = (π/n) a1-n ec(π/2n)
.

5 marks

Answer

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b

Evaluate

∫0π/2 sin7x cos4x dx
using Beta and Gamma functions.

5 marks

Answer

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OR
5

Prove that

∫0π/2 dθ / √(1 - 1/2 sin2θ) = [Γ(1/4)]2 / (2√π √2)
.

10 marks

Answer

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610 marks
a

Evaluate

∫01 ∫0√(1-x2) ∫0√(1-x2-y2) 1/√(1-x2-y2-z2) dzdydx
by changing to spherical polar coordinates.

5 marks

Answer

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b

Evaluate the integral

∫01 ∫0x ∫0x+z (x+y+z) dzdydx
.

5 marks

Answer

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OR
7

Find by triple integration, the volume of the paraboloid of revolution x2 + y2 = 4z cut off by the plane z = 4.

10 marks

Answer

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8

Prove the following vector identities: a) ∇(φ1φ2) = φ1∇φ2 + φ2∇φ1 b) ∇×(∇φ) = 0.

10 marks

Answer

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OR
9

If R = xi + yj + zk, show that: a) ∇R = 3 b) ∇(1/r) = -R/r3 c) ∇(rn) = nrn-2R d) ∇×(a×R) = 2a, where a is a constant vector and r = |R|.

10 marks

Answer

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10

State the Stokes' theorem. Verify it for the vector field F = (x2-y2)i - 2yzj + yzk over the upper half surface of x2 + y2 + z2 = 1, bounded by its projection on the xy-plane.

10 marks

Answer

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OR
11

State the Green's theorem in a plane. Verify it for ∮C (ex sin y) dx + (ex cos y) dy where C is the rectangle with the vertices (0,0), (π, 0), (π, π/2) and (0, π/2).

10 marks

Answer

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This page contains the question paper of MATHEMATICS-II from JNTU for B.Tech ME I Year I-I, December - 2017, R16.

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