Test: Partial Derivatives, Gradient- 2


25 Questions MCQ Test Topicwise Question Bank for Electronics Engineering | Test: Partial Derivatives, Gradient- 2


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Attempt Test: Partial Derivatives, Gradient- 2 | 25 questions in 75 minutes | Mock test for GATE preparation | Free important questions MCQ to study Topicwise Question Bank for Electronics Engineering for GATE Exam | Download free PDF with solutions
QUESTION: 1

 f(x, y) = x2 + xyz + z Find fx at (1,1,1)

Solution:

fx = 2x + yz

Put (x,y,z) = (1,1,1)

fx = 2 + 1 = 3.

QUESTION: 2

Eight people are planning to share equally the cost of a rental car. If one person withdraws from the arrangement and the others share equally the entire cost of the car, then the share of each of the remaining persons increased by:

Solution:

QUESTION: 3

The minimum point of the function f(x) = (x2/3) – x is at 

Solution:

Correct Answer :- a

Explanation : f(x) = (x^2/3) - x

f'(x) = 2/3(x-1/2) - 1

f"(x) = -1/3(x-3/2)

For critical points. f′(x)=0

=> 2/3(x-1/2) - 1 = 0 

f has minimum value of x = 1

QUESTION: 4

If x=a(θ+ sin θ) and y=a(1-cosθ), then dy/dx will be equal 

Solution:

QUESTION: 5

The minimum value of function y = x2 in the interval [1, 5] is  

Solution:

y =x 2 is strictly increasing function on [1,5]

∴ y= x 2 has minimum value at x = 1 is 1.

QUESTION: 6

The function f(x) = 2x3 – 3x2 – 36x + 2 has its maxima at  

Solution:

QUESTION: 7

What should be the value of λ such that the function defined below is continuous at x = π/22? 

Solution:

By the given condition 

QUESTION: 8

Consider function f(x) =(x2-4)2 where x is a real number. Then the function has  

Solution:

QUESTION: 9

If f     where ai (i = 0 to n) are constants, then  

Solution:

  - Euler’s theorem for homogeneous function 

QUESTION: 10

Solution:

QUESTION: 11

A point on a curve is said to be an extremum if it is a local minimum or a local maximum. The number of distinct exterma for the curve 3x4 – 16x3 – 24x2 + 37 is 

Solution:

QUESTION: 12

∇ × ∇ × P, where P is a vector, is equal to  

Solution:
QUESTION: 13

The value of the integral of the function g(x, y) = 4x3 + 10y4 along the straight line segment from the point (0, 0) to the point (1, 2) in the x-y plane is  

Solution:

The equation of the line passing through (0,0) and (1,2)  is y = 2x 

Given y x, y ) = 4x3+ 10y4 = 4x3 + 10(2x )4 = 4x3+ 160xy

QUESTION: 14

If    is a differentiable vector function and f is a sufficient differentiable scalar function, then curl  

Solution:

QUESTION: 15

The temperature field in a body varies according to the equation T(x,y) = x3+4xy. The direction of fastest variation in temperature at the point (1,0) is given by 

Solution:

QUESTION: 16

The divergence of vector  

Solution:

QUESTION: 17

The divergence of the vector 

Solution:
QUESTION: 18

 Among the following, the pair of vectors orthogonal to each other is 

Solution:

Then we say that they are orthogonal.  Choice (c) is correct. 

QUESTION: 19

The directional derivative of the scalar function f(x, y, z) = x2 + 2y2 + z at the point P = (1,1, 2) in the direction of the vector 

Solution:

Required directional derivatives at P(1,1,-1) 

=2

QUESTION: 20

The Gauss divergence theorem relates certain  

Solution:
QUESTION: 21

If P, Q and R are three points having coordinates (3, –2, –1), (1, 3, 4), (2, 1, –2) in XYZ space, then the distance from point P to plane OQR (O being the origin of the coordinate system) is given by  

Solution:

The equation of the plane OQR is (O being origin). 

QUESTION: 22

Let x and y be two vectors in a 3 dimensional space and <x, y> denote their dot product. 

Then the determinant det 

Solution:

QUESTION: 23

If a - b = 3 and a2 + b2 = 29, find the value of ab.

Solution:

2ab = (a2 + b2) - (a - b)2

   = 29 - 9 = 20

   ab = 10.

QUESTION: 24

If a vector R(t)  has a constant magnitude, then  

Solution:

On analysing the given (a) option, we find that    will give constant magnitude, so first 
differentiation of the integration will be zero. 

QUESTION: 25

For the scalar field    magnitude of the gradient at the point(1,3) is   

Solution:

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