Jawaharlal Nehru Technological University Hyderabad

Jawaharlal Nehru Technological University Hyderabad B.Tech I MATHEMATICS - I Previous Question Paper (May - 2018 - R15)

B.Tech | I | I-I | R15 | May - 2018

Answer PaperPaper Code: 121ABMaximum Marks: 75Time: 3 hours

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.

Part A

125 marks
a

If A and B are square symmetric matrices of same order then prove that AB + BA is symmetric.

2 marks

Answer

Given that A and B are symmetric, we have AT = A and BT = B. To prove AB + BA is symmetric, we take its transpose: (AB + BA)T = (AB)T + (BA)T = BTAT + ATBT. Substituting the symmetric properties, this becomes BA + AB, which is equal to AB + BA. Thus, the matrix is symmetric.

b

If one of Eigen vectors of

[[2,2,0],[2,5,0],[0,0,3]]
is
[[1],[2],[0]]
, then find the corresponding Eigen value.

3 marks

Answer

Let A = [[2, 2, 0], [2, 5, 0], [0, 0, 3]] and v = [1, 2, 0]T. The eigenvalue λ satisfies Av = λv. Calculating Av: [[2, 2, 0], [2, 5, 0], [0, 0, 3]] * [1, 2, 0]T = [2(1)+2(2)+0(0), 2(1)+5(2)+0(0), 0(1)+0(2)+3(0)]T = [6, 12, 0]T. Since [6, 12, 0]T = 6 * [1, 2, 0]T, the eigenvalue λ = 6.

c

Find the value of c in Roll’s theorem for

f(x) = sin x
in
(0, π)
.

2 marks

Answer

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d

Find the stationary points of the following functions

x^3 + y^3 - 3axy
.

3 marks

Answer

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e

Evaluate

∫[0 to ∞] x^2 e^-x dx
.

2 marks

Answer

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f

Evaluate

∫[0 to 2] ∫[0 to x] y dy dx
.

3 marks

Answer

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g

Solve the differential equation

(D^2 - 4D + 13)y = 0
.

2 marks

Answer

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h

Evaluate

((D^2 + 1)x^-1)
.

3 marks

Answer

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i

Find

L[t e^t]
.

2 marks

Answer

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j

Find f(t), if

L[f(t)] = 1/(s^2-1)
. Hence find
L^-1[s^2/(s^2-1)]
using any theorem of Laplace transforms.

3 marks

Answer

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Part B

2

Test for the consistency and hence solve the system: x + y + z = 6, x – y + 2z = 5, 3x + y + z = 8, 2x – 2y + 3z = 7

If λ1, λ2, ..., λn are the Eigen values of a non-singular matrix A of order n then prove that the Eigen values of A^-1 are 1/λ1, 1/λ2, ..., 1/λn.

10 marks

Answer

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OR
3

Reduce the quadratic form 6x^2 + 3y^2 + 3z^2 - 4xy - 2yz + 4xz by orthogonal reduction to the canonical form.

10 marks

Answer

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4

Verify Lagranges mean value theorem for f(x) = log x in [1, e].

Find the maximum and minimum values of x^3 + y^3 - 3axy.

10 marks

Answer

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OR
5

If x = r cosθ and y = r sinθ, find J = ∂(x,y)/∂(r,θ) and verify that JJ' = 1.

10 marks

Answer

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6

Evaluate ∫[0 to a] ∫[0 to √(a^2-x^2)] x^2 √(x^2+y^2) dy dx.

Change the order of integration and evaluate ∫[0 to a] ∫[x to a/x] xy dy dx.

10 marks

Answer

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OR
7

Prove that ∫[0 to 1] x^n(1-x)^m dx = Γ(n+1)Γ(m+1)/Γ(n+m+2).

Evaluate ∫∫[0 to a] ∫[0 to √(a^2-x^2)] (x^2+y^2) dy dx by changing into polar coordinates.

10 marks

Answer

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8

Find the orthogonal trajectory of the family of ay^2 = x^3.

Solve the differential equation (D^2 + 9)y = cos 3x + sin 2x.

10 marks

Answer

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OR
9

If a population is increasing exponentially at the rate of 2% per year. What will be the percentage increase over a period of 10 years?

Solve by the method of variation of Parameters: d^2y/dx^2 + y = sec x.

10 marks

Answer

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10

Evaluate ∫[0 to ∞] (sin t)/t dt.

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

10 marks

Answer

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OR
11

Solve the differential equation (D^2 + 2D + 2)y = t^2, using Laplace transform given that y(0)=4, y'(0)=2.

10 marks

Answer

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About this paper

This page contains the question paper of MATHEMATICS - I from Jawaharlal Nehru Technological University Hyderabad for B.Tech AME I I-I, May - 2018, R15.

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