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MU Computer Engineering (Semester 3)
Applied Mathematics 3
May 2013
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) $Find\ L\left\{t\ e^{31}\sin t\right\}$
5 M
1 (b) Show that every square matrix can be uniquely expressed as the sum of a Hermitian and skew-Hermitian matrix.
5 M
1 (c) Find Z-transform and region of convergence of f(k)=3k, k?0.
5 M
1 (d) Find the Fourier expansion of f(x)= x2 where -π ≤x ≤π.
5 M

2 (a) Prove that following matrix is orthogonal and hence find its inverse.
$A=\frac{1}{9}\left[\begin{array}{ccc}-8 & 4 & 1 \\1 & 4 & -8 \\4 & 7 & 4\end{array}\right]$
6 M
2 (b) $Find\ L^{-1}\left\{\frac{s+2}{{\left(s^2+4s+5\right)}^2}\right\}$
6 M
2 (c) "Obtain the Fourier expansion of $f\left(x\right)={\left(\frac{\pi{}-x}{2}\right)}^2$ in the internal and 0≤x≤2π and f(x+2π)=f(x). Also deduce that,
$\left(i\right)\ \frac{{\pi{}}^2}{6}=\frac{1}{1^2}+\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}$
$\left(ii\right)\frac{{\pi{}}^4}{90}=\frac{1}{1^4}+\frac{1}{2^4}+\frac{1}{3^4}+\frac{1}{4^4}+\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}$ "
8 M

3 (a) Investing for what values of ? and ? the equations.
x+y+z=6
x+2y+3z=10
x+2y+?z=? have,
(i) No Solution
(ii) a unique solution
(iii) Infinite no. of solutions.
6 M
3 (b) Obtain complex form of Fourier series for f(x)=eax (-π,π) where is not integer.
6 M
3 (c) Solve (D2 - D - 2) y=20 sin 2t with y(0)=1, y'(0)=2.
8 M

4 (a) Find Laplace transform of
$f\left(t\right)=a\sin{pt\ 0 \ < t\leq{}\frac{\pi{}}{p}}\\ f\left(t\right)=0\frac{\pi{}}{P}<t\leq{}\frac{2\pi{}}{P} \\ and \ f\left(t\right)=\left(t+\frac{2\pi{}}{P}\right)$
6 M
4 (b) Find the inverse Z-transform for
$f\left(z\right)=\frac{1}{\left(z-3\right)\left(z-2\right)}$
for 2<|z|<3.
6 M
4 (c) Find inverse Laplace transform of
$\left(i\right)\ \frac{e^{4-3s}}{{\left(s+4\right)}^{\frac{5}{2}}}\\ (ii)\tan^{-1}\frac{2}{s}$
8 M

5 (a) Examine whether the following vectors are linearly independent or dependent [2,1,1], [1,3,1], [1,2,-1]
6 M
5 (b) Using Convolution theorem prove that
$l^{-1}\left[\frac{1}{s}\ ln\ \left(\frac{s+1}{s+2}\right)\right]=\ \int_0^t\left(\frac{e^{-2u}-e^{-u}}{u}\right)du\$
6 M
5 (c) Using Fourier cosine Integral prove that
$e^{-x}\cos{x=\frac{1}{\pi{}}\int_0^{\infty{}}\frac{w^2+2}{w^4+4}\ \cos{wx\ dw}}$
8 M

6 (a) Find the Fourier Transform 0+f(x)=e-1x1
6 M
6 (b) Find z[f(x)] where $f\left(k\right)=\cos{\left(\frac{k\pi{}}{u}+a\right)}$ where k≥0.
6 M
6 (c) Find Fourier expansion of f(x)=2x - x2 where 0 ≤ x ≤ 3 and period is 3.
8 M

7 (a) Reduce the following matrix to noraml form and find its rank.
$A=\left[\begin{array}{ccc}1 & -1 & 3 & 6 \\1 & 3 & -3 & -4 \\5 & 3 & 3 & 11\end{array}\right]$
6 M
7 (b) $Evalute\ \int_0^{\infty{}}\frac{\cos{6t-\cos{4t}}}{t}dt$
6 M
7 (c) Show that the set of function
$\sin{\left(\frac{\pi{}x}{2L}\right)},\sin{\left(\frac{3\pi{}x}{2L}\right)},\sin{\left(\frac{5\pi{}x}{2L}\right)},\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}\bullet{}$
is orthogonal over..(0,L) Hence construct corresponding orthonormal set.
8 M

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