GATE EE 2015 SET 2


Question 1
Given f(z)=g(z)+h(z), where f, g, h are complex valued functions of a complex variable z. Which one of the following statements is TRUE?
A
If f(z) is differentiable at z_0, then g(z) and g(z) are also differentiable at z_0.
B
If g(z) and h(z) are differentiable at z_0, then f(z) is also differentiable at z_0.
C
If f(z) is continuous at z_0, then it is differentiable at z_0.
D
If f(z) is differentiable at z_0, then so are its real and imaginary parts.
Engineering Mathematics   Complex Variables
Question 2
We have a set of 3 linear equations in 3 unknowns. 'X \equiv Y' means X and Y are equivalent statements and 'X\not\equiv Y' means X and Y are not equivalent statements.

P: There is a unique solution.
Q: The equations are linearly independent.
R: All eigenvalues of the coefficient matrix are nonzero.
S: The determinant of the coefficient matrix is nonzero.

Which one of the following is TRUE?
A
P\equiv Q\equiv R\equiv S
B
P\equiv R\not\equiv Q\equiv S
C
P\equiv Q\not\equiv R\equiv S
D
P\not\equiv Q\not\equiv R\not\equiv S
Engineering Mathematics   Linear Algebra
Question 2 Explanation: 
\begin{aligned} a_{11}x_1+a_{12}x_2+a_{13}x_3 &=b_1 \\ a_{21}x_1+a_{22}x_2+a_{23}x_3 &=b_2 \\ a_{31}x_1+a_{32}x_2+a_{33}x_3 &=b_3 \\ \begin{bmatrix} a_{11} & a_{12} & a_{13}\\ a_{21} & a_{22}& a_{21}\\ a_{31}& a_{32} &a_{33} \end{bmatrix}\begin{bmatrix} x_1\\ x_2\\ x_3 \end{bmatrix}&= \begin{bmatrix} b_1\\ b_2\\ b_3 \end{bmatrix} \end{aligned}
if |A|\neq 0 then AX=B can be written as X=A^{-1}B
It leads unique solutions.
If |A|\neq 0 then \lambda _1 \cdot \lambda _2\cdot \lambda _3\neq 0 each \lambda _i is non-zero.
If |A|\neq 0 then all the row (column) vectors of A are linearly independent.


Question 3
Match the following.
A
P-2 Q-1 R-4 S-3
B
P-4 Q-1 R-3 S-2
C
P-4 Q-3 R-1 S-2
D
P-3 Q-4 R-2 S-1
Electromagnetic Fields   Coordinate Systems and Vector Calculus
Question 3 Explanation: 
Stokes theorem \oint \vec{A}\cdot dl=\int \int (\triangledown \times A)\cdot \hat{n}ds
Gauss theorem \int \int D\cdot ds=Q
Divergence theorem \oint \oint A\cdot \hat{n}ds=\int \int \int \triangledown \cdot \bar{A}dV
Cauchy integral theorem \oint _cf(z)dz=0
Question 4
The Laplace transform of f(t)=2\sqrt{t/\pi } is s^{-3/2}. The Laplace transform of g(t)=\sqrt{1/\pi t} is
A
3s^{-5/2}/2
B
s^{-1/2}
C
s^{1/2}
D
s^{3/2}
Signals and Systems   Laplace Transform
Question 4 Explanation: 
Given that,
f(t)=2\sqrt{\frac{t}{\pi}}\rightleftharpoons F(s)=s^{-3/2}
By using property of differentiation In time,
\begin{aligned} \frac{df(t)}{dt}&\rightleftharpoons sF(s) \\ \Rightarrow \; \frac{2}{\sqrt{\pi}}\cdot \frac{1}{2}t^{-1/2}&\rightleftharpoons sF(s) \\ \Rightarrow \; \frac{1}{\sqrt{\pi t}}&\rightleftharpoons s\cdot s^{-3/2} \\ \Rightarrow \; \frac{1}{\sqrt{\pi t}}&\rightleftharpoons s^{-1/2} \end{aligned}
Question 5
Match the following.
A
P-1 Q-2 R-1 S-3
B
P-1 Q-2 R-1 S-3
C
P-1 Q-2 R-3 S-3
D
P-3 Q-1 R-2 S-1
Electrical and Electronic Measurements   Galvanometers, Voltmeters and Ammeters




There are 5 questions to complete.