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JNTU B.Tech II MATHEMATICS-II Previous Question Paper (March-2021 - R15)

B.Tech | II | I | R15 | March-2021

Answer PaperPaper Code: 123AA/113AAMaximum Marks: 75Time: 3 hours

Answer any five questions. All questions carry equal marks.

Main

115 marks
a

Find the unit normal vector to the surface x3+y3+z3=3 at the point (1, 2, -1).

7 marks

Answer

Let the surface be defined by the function f(x, y, z) = x3 + y3 + z3 - 3 = 0. The normal vector to the surface at any point is given by the gradient vector ∇f.

∇f = (∂f/∂x)i + (∂f/∂y)j + (∂f/∂z)k = 3x2i + 3y2j + 3z2k

Evaluating the gradient at the point (1, 2, -1):

∇f(1, 2, -1) = 3(1)2i + 3(2)2j + 3(-1)2k = 3i + 12j + 3k

The magnitude of the gradient vector is:

|∇f| = √(32 + 122 + 32) = √(9 + 144 + 9) = √162 = 9√2

The unit normal vector n is given by ∇f / |∇f|:

n = (3i + 12j + 3k) / 9√2 = (1/3√2)i + (4/3√2)j + (1/3√2)k
b

Evaluate by stoke’s theorem ∫(ex dx + 2y dy - dz) where c is the curve x2+y2=9 and z=2.

8 marks

Answer

Stokes' theorem states that ∫C F · dr = ∫∫S (∇ × F) · n dS. Here, F = exi + 2yj - k.

First, calculate the curl of F:

∇ × F = | i j k |
| ∂/∂x ∂/∂y ∂/∂z |
| ex 2y -1 |
= i(0 - 0) - j(0 - 0) + k(0 - 0) = 0

Since the curl of the vector field F is the zero vector, the surface integral over any surface S bounded by the curve C is equal to zero.

∫∫S (0) · n dS = 0

Therefore, the line integral ∫C (ex dx + 2y dy - dz) = 0.

2

If f = 3x2yz2i + x2z2j + 2x3yz k. Show that ∫f∙dr over C is independent of the path of integration. Hence evaluate the integral when C is any path joining (0, 0, 0) to (1, 2, 3).

15 marks

Answer

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3

Obtain the half range cosine and sine series for the function f(x) = x when 0 < x < π.

15 marks

Answer

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415 marks
a

Find the missing term in the following data:

x01234
y139-81
7 marks

Answer

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b

Fit a straight line to the following data by the method of least square:

x01234
y11.83.34.56.5
8 marks

Answer

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5

Solve the system of equations:

2x + y + z - 2w = -10
4x + 2z + w = 8
3x + 2y + 2z = 7
x + 3y + 2z - w = -5

using LU decomposition method.

15 marks

Answer

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6

Determine the largest eigen value and the corresponding eigenvector of the matrix:

4 1 0
1 20 1
0 1 4

to 3 correct decimal places using the power method.

15 marks

Answer

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7

Fit a curve of the form y = a/x + bx to the data given below:

x1.01.21.41.61.8
y00.12800.54401.29602.4320
15 marks

Answer

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8

Evaluate ∫(1/(1+x2)) dx from 0 to 1 by taking h = 1/6 using:

15 marks
a

Simpson’s 1/3rd rule

8 marks

Answer

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b

Simpson’s 3/8th rule

7 marks

Answer

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This page contains the question paper of MATHEMATICS-II from JNTU for B.Tech AE II I, March-2021, R15.

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