Mathematics I (Calculus) 2074

Question Paper Details
Tribhuwan University
Institute of Science and Technology
2074
Bachelor Level / First Semester / Science
Computer Science and Information Technology ( MTH112 )
( Mathematics I (Calculus) )
Full Marks: 80
Pass Marks: 32
Time: 3 hours
Candidates are required to give their answers in their own words as far as practicable.
The figures in the margin indicate full marks.

Attempt any three questions.

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1. (a) A function is defined by ,  calculate f(-1),f(3), and sketch the  graph.(5)

5 marks
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Given,

Since -1<0, f(-1) = -1 + 2 = 1

Since 3>0, f(3) = 1 - 3 = -2

To draw graph, calculating the points:

For f(x) = x+2 if x<0

    f(-1) = -1+2 =1   (-1, 1)

    f(-2) = -2+2 = 0   (-2, 0)

    f(-3) = -3+2 = -1   (-3, -1) and so on.

For f(x) =1-x if x>0

    f(1) = 1-1 = 0   (1, 0)

    f(2) = 1-2 = -1   (2, -1)

    f(3)= 1-3 = -2   (3, -2) and so on.

Plotting these points of both functions we get;


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    (b) Prove that  the does not exist.

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Given,

Now,


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2. (a) Find the derivative of f(x) = √x and to state the domain of f

5 marks
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Given

For domain,   is exist only when x>0.

Thus, domain is (0, ∞).

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    (b) Estimate the area between the curve y2 = x and the lines x=0 and x=2.

1 marks
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Given

Given equation is the parabola that has the vertex (0, 0) and the line of symmetry is y = 0 with x>=0.

Given line are:

x = 0 & x =2

Sketch of the given curve is:

Area of bounded region 


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3. (a) Find the Maclaurin series for ex and prove that it represents ex for all x.

4 marks
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Now,

Let d is any positive number with  then 

So, by Taylor’s inequality

 for 

Since  is a finite value. So


i.e.

 for all values of x.

 This implies that series converges to ex for every value of x.

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    (b) Define initial value problem. Solve that initial value problem of y' + 5y = 1, y(0) = 2.

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The problem of finding a function y of x when we know its derivative and its value y0 at a particular point x0 is called an initial value problem.

Given,

Comparing given equation with we have

P = 5 and Q = 1

Now

Applying the initial condition y(0)=2

Applying this value, we have:


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    (c) Find the volume of a sphere of radius r.

2 marks
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The sphere of radius r can be obtained rotating the half circle graph (semi-circle) of the function  about the x-axis. 

The volume V is obtained as follows:

by the symmetry about the y-axis,


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4. (a) For what value of x does the series  converge?

5 marks
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Given series is,

The general term of the series is

So, apply ratio test

The series converges if x-3<1 Þ x<4

Therefore, the series converges for x<4.

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    (b) Calculate ∫ ∫ f(x, y)dA for f(x, y) = 100 − 6x2y and R: 0 ≤ x ≤ 2, −1 ≤ y ≤ 1.

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Attempt any ten questions:
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5. If  and , find gof and gog.

5 marks
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Given,

Now,


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6. Use continuity to evaluate the limit , 

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Since the function  is being a quotient of two continuous functions and   everywhere in their domain. In particular x = 4 and hence the quotient function f(x) is also continuous at x = 4.


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7. Verify Mean value theorem of f(x) = x3 − 3x + 3 for [−1,2].

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Given,

f(x) = x3-3x+3 

Since, f(x) = x3-3x+3  is continuous on [-1, 2] and f’(x) = 3x2-3 so, differentiable on (-1, 2).

Thus f(x) = x3-3x+3 satisfy the both conditions for mean value theorem. So, there exist  such that


Clearly 

Hence, mean value theorem satisfied.

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8. Sketch the curve y = x3 + x

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9. Determine whether the integer  is convergent or divergent .

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We have

Since the limit does not exist as a finite number so it divergent.

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10.Find the length of the arc of the semicubical parabola y2 = x3 between the point(1,1) and (4,8).

5 marks
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Given,

The arc length formula gives

If we substitute  then  when x = 4, u = 10.

Therefore,


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11. Find the solution of y" + 6y′ + 9 = 0, y(0) = 2, y(0) = 1.

5 marks
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Given

The characteristics equation of given differential equation is

Here the roots are real and equal.

The general solution is

Now, applying the condition y(0)=2

Again, 

Then, 

Applying the condition y’(0)=1

The particular solution of the given equation is


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12. Test the convergence of the series 

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Given series is

The general term of the series is

Here

So, the given series is divergent by D’Alembert ratio test.

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13. Define cross product of two vectors .if a=i+3j +4k and b-= 2i+7j=5k, find the vector a × b and b × a.

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If u=(u1, u2, u3) and v=(v1, v2, v3) then the cross product of u and v is a vector

It is also written as

Now,

Given that,

We have,

Thus,


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14. Define limit of a function . find 

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Let f(x, y) be a function of two variables x and y and L be a number. The we say L is the limit of f(x, y) at point (x0, y0) if


Now,

[This form is in  as ]

We can find its limit by rewriting it into the form   wherein L'Hospital's rule can be applied if it is applicable.


Applying L'Hospital's rule


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15. Find the extreme value of f(x, y) = y2 − x2 .

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Given

f(x, y) = y2-x2

Then

Also

For critical point,

This gives, x=0, y=0.

At point (0, 0)

Here, at point (0, 0)

and

The function has a saddle point at the (0, 0) and no local extreme values.

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