MORE IN Applied Mathematics - 3
MU Electronics and Telecom Engineering (Semester 3)
Applied Mathematics - 3
May 2012
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) Prove that
$\int_0^{\infty{}}e^{-t}\dfrac{{sin}^2t}{t}dt= \dfrac{1}{4} log 5$
5 M
1 (b) Is the matrix orthogonal ? If not then can it be converted to an orthogonal matrix :-
$A=\left[\begin{array}{ccc}-8 & 1 & 4 \\4 & 4 & 7 \\1 & -8 & 4\end{array}\right]$
5 M
1 (c) Obtain complex form of Fourier series for f(x) = eax in (-l ,l).
5 M
1 (d) Find the Z-transform of f(k) =ak, k≥0.
5 M

2 (a) Find the Fourier sine transform of f(x) if \begin {align*} f(x)&=\sin kx, &0 \le x <a \\ &=0, &x>a \end{align*}
6 M
2 (b) Find the Matrix A if
$\left[\begin{array}{cc}2 & 1 \\3 & 2\end{array}\right]\ A\ \left[\begin{array}{cc}-3 & 2 \\5 & -3\end{array}\right]=\ \left[\begin{array}{cc}-2 & 4 \\3 & -1\end{array}\right]$
6 M
2 (c) (D2- 3D+2) y=4 e21, with y(0) = -3, y'(0)=5 solve using Laplace transform.
8 M

3 (a) Reduce the matrix to normal form and find its rank :-
$\left[\begin{array}{cccc}2 & 3 & -1 & -1 \\1 & -1 & -2 & -4 \\3 & 1 & 3 & -2 \\6 & 3 & 0 & -7\end{array}\right]$
6 M
3 (b) Find the inverse Laplace transform of ?
$\left(i\right)\ \frac{e^{-2s}}{s^2+8s+25} \\ \left(ii\right)\ \frac{e^{-3s}}{{\left(s+4\right)}^3}$
6 M
3 (c) $\left.\begin{matrix} f(x)&= \pi x 0\leq x \leq 1 \\ f(x)&=\pi (2-x)1 \leq x \leq 2 \end{matrix}\right\} with \ period \ 2$
Find the Fourier series expansion
8 M

4 (a) Show that the set of functions ${\ \left(\frac{\pi{}x}{2l}\right), sin\left(\frac{3\pi{}x}{2l}\right),\ \sin\left(\frac{5\pi{}x}{2l}\right),.....}$is orthogonal over (0,l).
6 M
4 (b) If f(k)= 4kU(K), g(k)= 5kU(k), then find the z-transform of f(k) x g(k).
6 M
4 (c) Solve the following equations by Gauss-Seidel Method.
28x+4y-z=32
2x+17y+4z=35
x+3y+10z=24.
8 M

5 (a) Obtain Fourier series for
${\ f(x) = x + \frac{\pi{}}{2}, -\pi{} < x < 0} \\ {= \frac{\pi{}}{2}-x\ 0 < x < \pi{}}$
Hence deduce that, ${\ \frac{\pi^2}{8} = \frac{1}{1^2} + \frac{1}{3^2} + \frac{1}{5^2} + ....}$
6 M
5 (b) State Convolution theorem and hence find inverse Laplace transform of the function using the same :-
$f(s)\ =\frac{{\left(s+3\right)}^2}{{\left(s^2+6s+5\right)}^2}$
6 M
5 (c) For what value of λ the equations 3x-2y+ λ z=1, 2x+y+z=2, x+2y- λz= -1 will have no unique solution ? Will the equations have any solution for this value of λ ?
8 M

6 (a) Show that every square matrix A can be uniquely expressed as P+iQ when P and Q are Hermitian matrices
6 M
6 (b) If L[f(t)] = f(s), then prove that L[ tn f(t)] = (-1)n dn/dsn f(s), Hence find the Laplace transform of f(t) = t cos2t
6 M
6 (c) Obtain the half rang sine series for f(x) when
${\ f(x) = x 0 < x < \frac{\pi{}}{2}}\\{= \pi{} - x \frac{\pi{}}{2}< x < \pi{}} \\ Hence \ find \ the \ sum \ of \ \sum_{2n-1}^{\infty{}}\ \frac{1}{n^4}$
8 M

7 (a) Find the Fourier transform of-
f(x) = (1-x2), |x|<|
= 0 , |x|>|,
then $f\left(s\right)=\ -2\sqrt{\frac{2}{\pi{}}}\left[\frac{scoss-sins}{s^3}\right]$
6 M
7 (b) Find the inverse z transform of $F\left(z\right)=\ \frac{z}{\left(z-1\right)\left(z-2\right)},\ \left\vert{}z\right\vert{}>2$
6 M
7 (c) Find the non-singular matrices P and Q such that -
$A=\ \left[\begin{array}{ccc}1 & 2 & 3 & 2 \\2 & 3 & 5 & 1 \\1 & 3 & 4 & 5\end{array}\right]$
is reduced to normal form. Also find its rank.
8 M

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