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SE-Comps_SEM3 M3 DEC17

(3 hours) $\hspace{70mm}$ [Max. Marks 80]

N.B. :

1. Question no. 1 is compulsory.

2. Assume suitable data if necessary.

3. Attempt any three questions from remaining questions.

Q.1

a) Find the Laplace transform of $\frac{1}{t}e^{-t} sint$ .

b) Find the inverse Laplace transform of $\frac{1}{\sqrt{2s-1}}$ .

c) Find the function f(z)= sinh z and find f'(z)in terms of z.

d) Find the Fourier series of f(x)=x in (0,$2\pi$).

Q.2

a) Use laplace transform to prove $\int_{0}^{\infty }{e^{-2t}\frac{\sin ^{2}t}{t}dt}$.

b) If {f(k)} = | 4^{k} , 3^{k} | , find Z{f(k)}.

c) Show that the function u = $\cos$x $\cos$y is a harmonic function find the harmonic conjugate of and the corresponding analytic function.

Q.3

a) Find the equation of the line regression of Y on X for the following data

X 5 6 7 8 9 10 11
Y 11 14 14 15 12 17 16

b) Find the Bilinear transformation which maps the points (1,-1 ,2) on z plane on to (0,2, -i) respectively of w plane.

c) Find the half range sine series for f(x) = $x , 0 \lt x \lt \frac{\pi }{2}$

$\hspace{64mm}$ $\pi -x , \frac{\pi }{2} \lt x \lt \pi$

Hence find the sum of $\sum_{(2n-1)}^{\infty }{\frac{1}{n^{4}}}$ .

Q.4

a) Find the inverse Laplace transform by using convolution theorem $\frac{1}{(s-a)(s+a)^{2}}$.

b) Find the inverse Z transform of $\frac{1}{(z-a)^{2}} \vert z\vert \lt a$ , $\frac{1}{(z-3)(z-2)} \vert z\vert \gt 3$.

c) Calculate the coefficient of correlation of X and Y from the following data

X 8 8 7 5 6 2
Y 3 4 10 13 22 8

Q.5

a) Using Laplace transform evaluate $\int_{0}^{\infty }{e^{-t}(1+2t-t^{2}+t^{3})H(t-1)dt}$.

b) Show that the set of functions cos x cos 2x cos 3x is a set of orthogonal functions over [ - $\pi$ , $\pi$ ] . Hence construct a set of Orthonormal functions.

c) Solve using Laplace transform $(D^{3}-2D^{2}+5D)y=0$, y(0)=0, y'(0)=0, y''(0)=1.

Q.6

a) Find the complex form of Fourier series f(x)= 2x in (0,2$\pi$).

b) If f(z) and $\bar{f(z)}$ prove that f(z) is constant.

c) Fit a curve of form $y=ab^{x}$ from the data

X 1 2 3 4 5 6
Y 151 100 61 50 20 8