Question Paper: Applied Mathematics 4 : Question Paper May 2014 - Electronics Engineering (Semester 4) | Mumbai University (MU)
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## Applied Mathematics 4 - May 2014

### Electronics Engineering (Semester 4)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.
1(a) prove that Eigen values of a hermitian matrix are real.(5 marks) 1(b) Evaluate $$\oint_{c} \dfrac{e^{kx}}{z}dz$$over the circle |z|=1 and k is real. Hence prove that $$\int_{0}^{\pi}c^{k \cos \theta}\cos(k \sin \theta)d \theta =\pi$$(5 marks) 1(c) Find the extremal of $$\int_{x_{2}}^{x_{1}}(16y^{2}-(y)^{2}+x^{2})dx$$(5 marks) 1(d) Find a vector orthogonal to both u =(-6,4,2)and v=(3,1,5).(5 marks) 2(a) Find the curve y=f(x)for which $$\int_{x_{1}}^{x_{2}}y\sqrt{1+(y)^{2}}dx$$is minimum subject to the constraint $$\int_{x_{1}}^{x_{2}}\sqrt{1+(y)^{2}}dx=l$$(6 marks) 2(b) Find eigen values and eigen vectors of the matrix $$A=\begin{bmatrix}-2 &5 &4 \\ 5&7 &5 \\ 4&5 &-2 \end{bmatrix}$$(6 marks) 2(c) Obtain Taylors series and two distinct Laurents series expansion of $$f(z)=\dfrac{z^{2}-1}{z^{2}+5z+6}$$about z=0, indicating region of convergence.(8 marks) 3(a) State Cayley-Hamilton Theorem, hence deduce that A8=6251, where $$A=\begin{bmatrix} 1&2 \\ 2 &-1 \end{bmatrix}$$(6 marks) 3(b) Using calculus of Residues,prove that $$\int_{0}^{2\pi}e^{\cos \theta}\cos(\sin \theta -n \theta)d \theta=\dfrac{2\pi}{n!}$$ (6 marks) 3(c) Find the plane curve of fixed perimeter and maximum area.(8 marks) 4(a)

State Cauchy-Schwartz inequality and hence show that $$(x^{2}+y^{2}+z^{2})^{1/2} \ge\dfrac{1}{13}(3x+4y+12z),x,y,z$$ are positive.

(6 marks) 4(b) Reduce the quadratic form Q =x2+y2-2z2-4xy-2yz+10xz to to Canonical form using congruent transformation.(6 marks) 4(c) (ii)

Show that the matrix $A=\begin{bmatrix} 5 &-6 &-6 \\\\ -1&4 &2 \\\\ 3 &-6 &-4 \end{bmatrix}$is Derogatory.

(4 marks)
4(c)(i) If $$A=\begin{bmatrix} \pi/2 &3\pi/2 \\ \pi&\pi \end{bmatrix}$$, find Sin A(4 marks) 5(a)

Using Rayleigh-Ritz method,find an appropriate solution for the extremal of the functional $$I \left [ y(x) \right ]=\int_{0}^{1}\left [ xy+\dfrac{1}{2}(y^{'})^{2}\right]dx$$ subject to y(0)=y(1)=0.

(6 marks)
5(b) Find an orthonormal basis of the following subspace of R3,S ={[1,2,0][0,3,1]}.(6 marks) 5(c)

Is the matrix $A=\begin{bmatrix} 2 & 1 &1 \\\\ 1& 2 &1 \\\\ 0 & 0 & 1 \end{bmatrix}$diagonalizable.If so find diagonal form and transforming matrix.

(8 marks)
6(a)

Find f(3),f'(1+i),f"(1-i),if f(a) =$\int _{c}\dfrac{3x^{2}+11z+7}{z-a}dz$,c:|z|=2

(6 marks)
6(b)

Evaluate$\int_{0}^{\infty}\dfrac{x^{3}sin x}{(x^{2}+z^{2})^{2}}$using contour integration.

(6 marks)
6(c)

Find the singular value decomposition of the matrix A = $\begin{bmatrix}1 & 1\\\\ 1 & 1\\\\ 1 &-1\end{bmatrix}$

(8 marks)