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2022 103202

B.Tech 2nd Semester Exam., 2022

Time 3 hours
Full Marks 70
Instructions:
  • The marks are indicated in the right-hand margin.
  • There are NINE questions in this paper.
  • Attempt FIVE questions in all.
  • Question No. 1 is compulsory.

  1. Choose the correct option of the following (any seven):

Q1.a

The inverse of a symmetric matrix is

a)

symmetric

b)

skew-symmetric

c)

diagonal matrix

d)

None of the above

Q1.b

If A is a matrix such that there exists a square sub-matrix of order r and every square sub-matrix of order r + 1 or more is singular, then

a)

rank of A = r + 1

b)

rank of A = r

c)

rank of A > r

d)

rank of A > r + 1

Q1.c

Let a, b, c be positive real numbers, then the following system of equations in x, y and z

$ \frac{x^2}{a^2} + \frac{y^2}{b^2} - \frac{z^2}{c^2} = 1, \frac{x^2}{a^2} - \frac{y^2}{b^2} + \frac{z^2}{c^2} = 1, -\frac{x^2}{a^2} + \frac{y^2}{b^2} + \frac{z^2}{c^2} = 1 $

has

a)

no solution

b)

unique solution

c)

infinitely many solutions

d)

finitely many solutions

Q1.d

If $ f(x) = 0 $ is an algebraic equation, then Newton-Raphson method is given by $ x_{n+1} = x_n - \frac{f(x_n)}{?} $

a)

f(xn1)f(x_{n-1})

b)

f(xn1)f'(x_{n-1})

c)

f(xn)f'(x_n)

d)

f(xn)f''(x_n)

Q1.e

Gauss forward interpolation formula involves

a)

even differences above the central line and odd differences on the central line

b)

even differences below the central line and odd differences on the central line

c)

odd differences below the central line and even differences on the central line

d)

odd differences above the central line and even differences on the central line

Q1.f

How many prior value(s) is/are required to predict the next value in Adams-Bashforth-Moulton method?

a)

1

b)

2

c)

3

d)

4

Q1.g

What is/are the order(s) of the predictor and corrector in Milne's predictor-corrector method?

a)

1

b)

2

c)

3

d)

4

Q1.h

A sufficient condition for convergence for the system of equations $ Au = d $ obtained, when we apply finite difference methods for Laplace's or Poisson equation is

a)

the coefficient matrix A of the system of equations is diagonally dominant

b)

the coefficient matrix A of the system of equations is non-singular

c)

the coefficient matrix A of the system of equations is singular

d)

None of the above

Q1.i

$ L(\sqrt{t}) = $

a)

Γ(3/2)s3/2\frac{\Gamma(3/2)}{s^{3/2}}

b)

Γ(1/2)s1/2\frac{\Gamma(1/2)}{s^{1/2}}

c)

Γ(1/2)s3/2\frac{\Gamma(1/2)}{s^{3/2}}

d)

Γ(3/2)s1/2\frac{\Gamma(3/2)}{s^{1/2}}

Q1.j

$ L^{-1}(e^{-as} F(s)) = $

a)

f(t)u(t)f(t)u(t)

b)

f(ta)u(t)f(t-a)u(t)

c)

f(ta)u(ta)f(t-a)u(t-a)

d)

None of the above

Q2.a

Reduce the matrix to normal form and find its rank.

$ A = \begin{bmatrix} 2 & 3 & 4 & 5 \\ 3 & 4 & 5 & 6 \\ 4 & 5 & 6 & 7 \\ 5 & 6 & 7 & 8 \end{bmatrix} $

Q2.b

For what values of k, the equation $ x + y + z = 1, 2x + y + 4z = k, 4x + y + 10z = k^2 $ has a solution?

Q3.a

Verify Cayley-Hamilton theorem for the matrix

$ A = \begin{bmatrix} 2 & 1 & 1 \\ 0 & 1 & 0 \\ 1 & 1 & 2 \end{bmatrix} $

Hence prove that

$ A^8 - 5A^7 + 7A^6 - 3A^5 + A^4 - 5A^3 + 8A^2 - 2A + I = \begin{bmatrix} 8 & 5 & 5 \\ 0 & 3 & 0 \\ 5 & 5 & 8 \end{bmatrix} $

Q3.b

Find a matrix P which transforms the matrix $ A = \begin{bmatrix} 1 & 0 & -1 \\ 1 & 2 & 1 \\ 2 & 2 & 3 \end{bmatrix} $ to diagonal form. Hence find $ A^4 $.

Q4.a

Find the smallest positive root of $ x^4 - x = 10 $ by using the Newton-Raphson method, correct to three decimal places.

Q4.b

Evaluate $ \Delta^2 \left( \frac{5x + 12}{x^2 + 5x + 6} \right) $; the interval of differencing being unity.

Q5.a

Derive the Newton's forward difference formula using the operator relations.

Q5.b

Using the trapezoidal rule, evaluate the integral $ I = \int_0^1 \frac{dx}{x^2 + 6x + 10} $, with 2 and 4 sub-intervals. Compare with the exact solution. Comment on the magnitudes of the errors obtained.

Q6.1

Using the Adams-Bashforth predictor-corrector equations, evaluate $ y(1.4) $, if y satisfies $ \frac{dy}{dx} + \frac{y}{x} = \frac{1}{x^2} $ and $ y(1) = 1, y(1.1) = 0.996, y(1.2) = 0.986, y(1.3) = 0.972 $.

Q7.1

Solve the equation $ u_{xx} = u_t $ subject to $ u(x, 0) = 0, u(0, t) = 0 $ and $ u(l, t) = t $, for two time steps by Crank-Nicolson method.

Q8.a

Find the inverse Laplace transform of $ \frac{s}{(s^2 + a^2)^3} $ with the help of convolution theorem.

Q8.b

Find the values of the integral $ \int_0^\infty e^{-3t} \frac{\sin^2 t}{t} dt $ with the help of Laplace transform.

  1. Find the solution of following differential equations by using Laplace transform :

Q9.a

$ t \frac{d^2y}{dt^2} + (1 - 2t) \frac{dy}{dt} - 2y = 0 $, when $ y(0) = 1, y'(0) = 2 $

Q9.b

$ \frac{\partial^2 y}{\partial t^2} = 9 \frac{\partial^2 y}{\partial x^2} $, where $ y(0, t) = 0, y(2, t) = 0 $ and $ y(x, 0) = 20 \sin 2\pi x - 10 \sin 5\pi x $


2021 103202

B.Tech 2nd Semester Exam., 2021

Time 3 hours
Full Marks 70
Instructions:
  • The marks are indicated in the right-hand margin.
  • There are NINE questions in this paper.
  • Attempt FIVE questions in all.
  • Question No. 1 is compulsory.

  1. Answer any seven of the following :

Q1.a

The eigenvalues of a matrix $ A $ are 2, 3, 1, then find the eigenvalues of $ A^{-1} + A^2 $.

Q1.b

If $ A $ and $ B $ are symmetric matrices, then prove that $ AB - BA $ is a skew-symmetric matrix.

Q1.c

Prove that the matrix

$ \frac{1}{3} \begin{bmatrix} -2 & 1 & 2 \\ 2 & 2 & 1 \\ 1 & -2 & 2 \end{bmatrix} $

is orthogonal.

Q1.d

Prove that $ \Delta = \frac{1}{2} \delta^2 + \delta \sqrt{1 + (\delta^2 / 4)} $.

Q1.e

Find the missing values in the table :

x4550556065
y3____2____-2.4
Q1.f

Use Euler's method to obtain an approximate value of $ y(0.4) $ for the equation $ y' = x + y, \ y(0) = 1 $ with $ h = 0.1 $.

Q1.g

Obtain the approximate value of $ y(1.2) $ for the initial value problem $ y' = 2xy^2, \ y(1) = 1 $ using Taylor series second-order method with step size $ h = 0.1 $.

Q1.h

Find the Laplace transform of $ \cos^2 3t $.

Q1.i

Find the inverse Laplace transform of $ \frac{s^3}{s^4 - a^4} $.

Q1.j

Evaluate : $ \int_0^\infty e^{-x^2} dx $.

Q2.a

Investigate for what values of $ \lambda $ and $ \mu $ do the system of equations $ x+y+z=6, \ x+2y+3z=10, \ x+2y+\lambda z=\mu $ have (i) no solution, (ii) unique solution and (iii) infinite solutions.

Q2.b

Find the rank of the matrix

$ \begin{bmatrix} 3 & 2 & -1 \\ 4 & 2 & 6 \\ 7 & 4 & 5 \end{bmatrix} $

by reducing it to normal form.

Q3.a

Verify Cayley-Hamilton theorem for the matrix

$ A = \begin{bmatrix} 2 & -1 & 1 \\ -1 & 2 & -1 \\ 1 & -1 & 2 \end{bmatrix} $

Hence compute $ A^{-1} $.

Q3.b

Reduce the matrix

$ P = \begin{bmatrix} 1 & 2 & -2 \\ 1 & 2 & 1 \\ -1 & -1 & 0 \end{bmatrix} $

to diagonal form.

Q4.a

Find a real root of the equation $ x \log_{10} x = 1.2 $ by Regula-Falsi method, correct to four decimal places.

Q4.b

The following table gives the population of a town during the last six censuses. Estimate the population in 1913 by Newton's forward difference formula :

Years191119211931194119511961
Population (in thousands)121520273952

Q5.a

Find $ \int_0^6 \frac{e^x}{1+x} dx $ approximately by using Simpson's 3/8 rule on integration.

Q5.b

Evaluate $ \int_0^8 x \sec x dx $ using eight intervals by Trapezoidal rule.

Q6.a

State convolution theorem of Laplace transform and using it find $ L^{-1} \left\{ \frac{1}{(s^2+4)(s+2)} \right\} $.

Q6.b

Use Laplace Transform to solve :

$ \frac{dx}{dt} + y = \sin t, \ \frac{dy}{dt} + x = \cos t $

given that $ x=2, \ y=0 $ at $ t=0 $.

Q7.a

Find the Fourier transform of $ f(x) $, defined by

$ f(x) = \begin{cases} 1, & |x| < a \\ 0, & |x| > a \end{cases} $

and hence evaluate $ \int_{-\infty}^\infty \frac{\sin as \cos sx}{s} ds $.

Q7.b

Evaluate : $ \int_0^\infty e^{-st} t^3 \sin t dt $.

Q8.a

Solve the initial value problem $ yy' = x, \ y(0)=1 $, using the Euler method in $ 0 \le x \le 0.8 $, with $ h=0.2 $ and $ h=0.1 $. Compare the results with the exact solution at $ x=0.8 $. Extrapolate the result.

Q8.b

Given the initial value problem $ \frac{dy}{dx} = \frac{y-x}{y+x}, \ y(0)=1 $. Find $ y(1) $ by Runge-Kutta fourth-order method taking $ h=0.5 $.

Q9.1

Obtain the approximate value of $ y(0.2) $ for the initial value problem $ y' = x^2 + y^2, \ y(0)=1 $. Using the methods $ y_{n+1} = y_n + h f(x_n, y_n) $ as predictor and $ y_{n+1} = y_n + \frac{h}{2} [f(x_n, y_n) + f(x_{n+1}, y_{n+1})] $ as corrector, with $ h=0.1 $. Perform two corrector iterations per step.


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