# Jawaharlal Nehru Technological University Anantapur 2008 B.Tech Supplimentary s, / MATHEMATICS-I - Question Paper

Code No: R05010102 Set No. 1

I B.Tech Supplimentary Examinations, Aug/Sep 2008

MATHEMATICS-I ( Common to Civil Engineering, Electrical & Electronic Engineering, Mechanical Engineering, Electronics & Communication Engineering, Computer Science & Engineering, Chemical Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Information Technology, Electronics & Control Engineering, Mechatronics, Computer Science & Systems Engineering, Electronics & Telematics, Metallurgy & Material Technology, Electronics & Computer Engineering, Production Engineering, Aeronautical Engineering, Instrumentation & Control Engineering and Automobile Engineering)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions All Questions carry equal marks

Test the following series for convergence or divergence.

1. (a (b ^{(c}

2. (a (b

3. (a (b

4. (a (b ^{(c}

5. (a (b

[5]

[5]

[6]

i

n^{2} 1

Test whether the following series is absolutely convergent.

E

n=1

n^{2}+1

State and prove Generalilzed mean value theorem.

Find the point with in a triangle such that the sum of the square of its distances from the three vertices is a minimum.

Find the envelope of the family of straight lines ^{x} cos e + ^{y} si^{n }e

1,9 being the [8+8]

parameter.

In the evolute of the parabola y^{2} = 4ax, show that the length of the curve from

its cusp x = 2a to the point where it meets the parabola y^{2} 2a(3y^{/}3 - 1)

Find the length of the arc of the curve y = log [^{e}*^{-1}

4ax is

_{x} 1 from x = 1 to x = 2

e^{x}+1 J

[8+8]

Form the differential equation by eliminating the arbitrary constant sin + e^{1/y} = c.

Solve the differential equation: dr + (2r cot9 + sin29) d9 = 0.

The rate at which the population of the city increases at any time is proportional to the population at that time. If there were 1,30,000 people in 1950 and 1,60,000 in 1980. What is the anticipated population in 2010? [3+7+6]

Solve the differential equation: (D^{2} + 4)y = sint + (1/3) sin3t + (1/5) sin5t, y(0) = 1, y '(0) = 3/35.

Solve the differential equation: (D^{2} + 1)y = x sinx by variation of parameters method. [8+8]

6. (a) Find L

sin^{2} t t

(c) Evaluate the integral / / /xy^{2}z dxdydz taken through the positive octant of

i^{2}. [5+5+6]

the sphere x^{2} + y^{2} + z^{2}

7. (a) Find a and b such that the surfaces ax^{2} - byz=(a + 2)x and 4ax^{2}y + z^{3}=4 cut orthogonally at (1, -1, 2).

(b) Show that F = (2xy + z^{3}) i + x^{2} j + 3 x z^{2} k is a conservative force field. Find the scalar potential and the work done by F in moving an object in this

field from (1, -2, 1) to (3,1,4).

[8+8]

[16]

8. Verify Greens theorem for f (x^{2} cos by) dx + (y + sin x)

where C is the rectangle bounded by (0,0) (n, 0) (n, 1) and (0,1).

I B.Tech Supplimentary Examinations, Aug/Sep 2008

MATHEMATICS-I ( Common to Civil Engineering, Electrical & Electronic Engineering, Mechanical Engineering, Electronics & Communication Engineering, Computer Science & Engineering, Chemical Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Information Technology, Electronics & Control Engineering, Mechatronics, Computer Science & Systems Engineering, Electronics & Telematics, Metallurgy & Material Technology, Electronics & Computer Engineering, Production Engineering, Aeronautical Engineering, Instrumentation & Control Engineering and Automobile Engineering)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions All Questions carry equal marks

Test the convergence of the series [5]

1. (a (b ^{(c}

2. (a (b

3. (a (b

4. (a (b ^{(c}

5. (a (b

6. (a (b

Find w^{hether the series -} 7P+T + Tk ^{-} 745+ +..........+ ^{conver}g^{es}

absolutely / conditionally. [5]

Verify Cauchys mean value theorem for f(x)=x3, g(x)=x2 in [1,2]. [6]

Show that the functions u = x+y+z , v = x^{2}+y^{2}+z^{2}-2xy-2zx-2yz and w = x^{3}+y^{3}+z^{3}-3xyz are functionally related. Find the relation between them.

Find the centre of curvature at the point of the curve \fx + = \fa.

Find also the equation of the circle of curvature at that point. [8+8]

Trace the Cissoid of Diocles : y^{2} (2a-x) = x^{3}.

Show that the surface area of the spherical zone contained between two parallel planes of distance h units apart is 2nah, where a is the radius of the sphere.

[8+8]

Form the differential equation by eliminating the arbitrary constant x tan(y/x) = c.

Find the orthogonal trajectories to x^{2} - y^{2} = a^{2}.

Radium decomposes at a rate proportional to the amount present at that time. If a fraction p of the original amount disappears in 1 year how much amount will remain at the end of 21 years. [3+7+6]

Solve the differential equation: (D^{2} + 1)y = e^{-x} + x^{3} + e^{x} sinx.

Solve (D^{2} + 4)y = sec2x by the method of variation of parameters. [8+8]

Find the Laplace transformation of e ^{2t} + 4t^{3} - 2 sin3t + 3cos3t.

Find L - ^{1} P - 3s^{2} + 6s - 4

^{L} _ (s^{2} -2s +2)^{2}

(c) Evaluate f J e ^{(x} +^{y 2} dxdy [5+6+5]

0 0

7. (a) Show that curl (r^{n}r) = 0

(b) Evaluate ff F.nds where F=zi+xj+3y^{2}zk where S is the surface of the cylin-

S

der x2+y2=1 in the first octant between z=0 and z=2 [8+8]

8. Verify Stokes theorem for the function F = x2 i + xy j integrated round the square whose sides are x = 0, y = 0, x = a and y = a in the plane z = 0. [16]

I B.Tech Supplimentary Examinations, Aug/Sep 2008

MATHEMATICS-I ( Common to Civil Engineering, Electrical & Electronic Engineering, Mechanical Engineering, Electronics & Communication Engineering, Computer Science & Engineering, Chemical Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Information Technology, Electronics & Control Engineering, Mechatronics, Computer Science & Systems Engineering, Electronics & Telematics, Metallurgy & Material Technology, Electronics & Computer Engineering, Production Engineering, Aeronautical Engineering, Instrumentation & Control Engineering and Automobile Engineering)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions All Questions carry equal marks

Test the convergence of the series nr [5]

1. (a (b ^{(c}

2. (a (b

3. (a (b

4. (a (b ^{(c}

5. (a (b

6. (a (b

Find the whether the series | 1 + 618150 6 g31 5 ' [2 + converges absolutely or conditionally. [6]

Verify Rolles theorem for f (x) = x2n-1 (a - x)2n in (0,a). [5]

Expand f(x,y) = e^{y}log(1+x) in powers of x and y.

Find the envelope of the family of straight lines X + f = 1 where a2 + b2 = k2, k being a constant. [8+8]

Trace the Cissoid of Diocles : y^{2} (2a-x) = x^{3}.

Show that the surface area of the spherical zone contained between two parallel planes of distance h units apart is 2nah, where a is the radius of the sphere.

[8+8]

Form the differential equation by eliminating the arbitrary constant sin + e^{1/y} = c.

Solve the differential equation: dr + (2r cot# + sin2O) dO = 0.

The rate at which the population of the city increases at any time is proportional to the population at that time. If there were 1,30,000 people in 1950 and 1,60,000 in 1980. What is the anticipated population in 2010? [3+7+6]

Solve the differential equation: y" - 4y^{;} + 3y = 4e^{3x},

y^{(0)} = ^{-1} y^{/(0)} = ^{3}

Solve the differential equation: (1 + x)^{2}dXy +(1+ x)+ y = 4 cos log(1 + x)

[8+8]

Find the Laplace transformation of e ^{2t} + 4t^{3} - 2 sin3t + 3cos3t.

Find L - 1 P - 3s^{2} + 6s - 4

^{Find }L _ (s^{2} -2s +2)^{2}

(c) Evaluate f J e ^{(x2}+^{y2)} dxdy [5+6+5]

0 0

7. (a) Find a unit normal vector to the surface x^{3}+y^{3}+ z^{3}=3 at the print (1, -2,-1)

(b) If F = (x^{2} y)i + (2xz y)j + z^{2}k, evaluate j F.dt along the straight line joining the points (0,0,0) to (1,2,4) [8+8]

8. (a) Apply Greens theorem to prove that the area enclosed by a plane curve is

| f (x dy - y dx ). Hence find the area of an ellipse whose semi major and

C

minor axes are of lengths a and b.

(b) Evaluate jj (y^{2}z^{2} i + z^{2}x^{2} j + z^{2}y^{2} k). N ds

S

where S is the part of the unit sphere above the xy- plane. [8+8]

'k 'k 'k 'k 'k

I B.Tech Supplimentary Examinations, Aug/Sep 2008

Time: 3 hours Max Marks: 80

Answer any FIVE Questions All Questions carry equal marks

1. (a) Test the convergence of the following series (log log n)n [5]

(b

Find the interval of convergence of the series

_{x + 1x3 + 13 + 13.5 + [5] x + 2 3 + 2 4 5 + 2.4.6 7 + ..........[5]}

2 4

Show that log (1 + e^{x}) = log 2 + x + xl i_ +..... and hence deduce that

^{(c}

2. (a (b

3. (a (b

4. (a

(b

(c

5. (a (b

6. (a

(b

(c

^{1 + x x3 + ..........[6]}

e^{x}+1 2 4 48

Expand sin (x+y) in powers of (x+y).

show that the evolute of cycloid x = a(9 - sin#), y = a(1 - cos#) is another cycloid x = a(# + sin#), y = - a(# - sin#) [8+8]

Trace the curve : r = a ( 1 + cos # ).

Find the length of the arc of the curve x = edsin#; y = edcos# from # = 0 to # = n/2. [8+8]

Obtain the differential equation of the co-axial circles of the system x^{2}+y^{2}+2ax + c^{2} = 0 where c is a constant and a is a variable parameter.

Solve the differential equation: dr = ^{x}~^{ycosx}

dx 1+sin x

22

Find the orthogonal trajectories of the co-axial curves x + = 1, being a parameter [3+7+6]

Solve the differential equation: (D^{2}-1)y= xsinx + x^{2} e^{x}.

Solve the differential equation: (x^{2}D^{2}+xD+4)y=log x cos (2logx). [8+8]

Find L

^{Fi}^{d L} [S2T\

Evaluate the integral / / /xy^{2}z dxdydz taken through the positive octant of the sphere x^{2} + y^{2} + z^{2}= a^{2}. [5+5+6]

7. (a) If 0=xy+yzzx and F = x^{2}yi + y^{2}zj + z^{2}xk, then find F grad 0 and F x grad

0 at (3,-1,2)

(b) Show that F=(y^{2}cosx+z^{2})i + (2ysinx-4)j+3xz^{2}k is irrotational and find its scalar potential [8+8]

8. Verify the Stokes theorem forF = yi + zj+xk and surface is the part of the sphere x^{2} + y^{2} + z^{2} = 1 above the xy plane. [16]

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