Showing posts with label Definite integrals. Show all posts
Showing posts with label Definite integrals. Show all posts

Sunday, January 17, 2016

27. Definite Integrals - Revision Facilitator



Revision Facilitator


Try to recollect relevant points on the topic.

If required right click on the topic and click on open in a new window to read the relevant material.

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The definite integral

Evaluation of definite integrals

Geometric interpretation of definite integral

Evaluation of integrals by substitution

Properties of definite integrals

Integral function

Summation of series using definite integral as the limit of a sum

Gamma function

Monday, November 17, 2008

The definite Integral - Definition

If F(x) is the antiderivative of a function f(x) continuous on (a,b)which means F'(x) = f(x) (a is less than x is less than b), then

∫f(x)dx {from a to b} = F(x) from a to b = F(b) - F(a)

Evluation of Definite Integrals

To find ∫f(x)dx from a to b

Find indefinite integral of ∫f(x)dx = ф(x)

Evaluate ф(b) and ф(a)

Calculate ф(b) - ф(a)

Geometric interpretation of definite integral

the definite integral represents the algebraic sum of the areas of the figures bounded by

the graph of the function y = f(x)
the x axis
the straight line x =a and x = b.

if the curve goes above and below the x axis in the interval a to b, the areas of above the x axis enter this sum with a plus sign, while those below the x axis enter it with a minus sign.

Evaluation of Definite Integrals by Substitution

If a substitution is done in a definite integral, such a substitution needs to be effected at three places.

1. in the integrand

2. in the differential

3. in the limits

Properties of definite integrals

Properties of definite integrals

1. ∫ab f(x)dx = -∫ba f(x)dx



2. ∫ab f(x)dx = ∫ac f(x)dx + ∫cb f(x)dx


3. ∫0a f(x)dx = ∫0a f(a-x)dx

4. If f(-x) = f(x) (means f is an even function), then
-aa f(x)dx = 2∫0a f(x)dx

5. If f(-x) = -f(x) (means f is an odd function), then
-aa f(x)dx = 0

6. ∫0af(x)dx = ∫0af(a-x)dx and
abf(x)dx = ∫abf(a+b-x)dx

7. ∫0af(x)dx = ∫0a/2f(x)dx+∫0a/2f(a-x)dx

Due to the above relation

0af(x)dx = 0 if f(a-x) = -f(x)
0af(x)dx = 2∫0a/2f(x)dx if f(a-x) = f(x)

8. If f is continuous on [a,b], then the integral function defined by g(x) = ∫axf(t)dt for x Є [a,b]is derivable on [a,b], and g'(x) = f(x) for x Є [a,b].


9. If f(x0 is periodic with period T then

abf(x)dx = ∫a+nTb+nTf(x)dx, where n is an integer.

In particular

0nTf(x)dx = n∫0Tf(x)dx






If m and M are the smallest and greatest values of a function f(x) on an interval [a,b], then m(b-a)≤∫abf(x)dx≤M(b-a)

Integral Function

If f(x) is a continuous function defined on [a,b]m then a function ф(x) defined by

ф(x) = ∫f(t)dt, (a to x); x belongs to [a,b] is called the integral function of the function f.

Summation of Series Using Definite Integral as the Limit of a Sum

∫f(x)dx (from a to b) = lim (h→0) h[f(a)+f(a+h)+f(a+2h)+...+f(a+(n-1)h)] where h = (b-a)/n

h→0 implies n→∞



∫f(x)dx (from 0 to 1) = lim (n→∞) (1/n)[Σf(r/n)(from r = to n-1)]

Gamma Function

If n is a positive number, then the improper integral

0 e-xxn-1dx is defined as a Gamma Function and is denoted by Γn.

Friday, November 7, 2008

IIT JEE Mathematics Study Guide 27. Definite Integrals and Revision Facilitator

Sections in the chapter

1 The definite integral

2 Evaluation of definite integrals

3 Geometric interpretation of definite integral

4 Evaluation of integrals by substitution

5 Properties of definite integrals

6 Integral function

7 Summation of series using definite integral as the limit of a sum

8 Gamma function

Study Plans

Day 1

1 The definite integral

2 Evaluation of definite integrals

3 Geometric interpretation of definite integral

4 Evaluation of integrals by substitution

Day 2

5 Properties of definite integrals - up to example 15

Day 3

5 Properties of definite integrals - From example 16 to 30

Day 4
Illustrative Objective Type Examples 1 to 20

Day 5

6 Integral function

7 Summation of series using definite integral as the limit of a sum

8 Gamma function

Day 6

I.O.T.E.: 21 to 44

Day 7

Objective Type Exercises 1 to 20

Day 8
O.T.E.: 21 to 40

Day 9
O.T.E.: 41 to 60

Day 10
O.T.E.: 61 to 80


Day 11
O.T.E.: 81 to 100


Day 12
O.T.E.: 101 to 120


Day 13
O.T.E.: 121 to 140


Day 14
O.T.E.: 141 to 160


Day 15
O.T.E.: 161 to 180

Revision Period

Day 16
O.T.E.: 181 to 190


Day 17
O.T.E.: 191 to 200


Day 18
O.T.E.: 201 to 210


Day 19
O.T.E.: 211 to 220


Day 20
O.T.E.: 221 to 223
Fill in the blank type exercise 1 to 5


Day 21
Fill in the blank type exercise 6 to 15


Day 22
Fill in the blank type exercise 16 to 25

Day 23
Fill in the blank type exercise 26 to 35

Day 24
Fill in the blank type exercise 36 to 46

Day 25
True/False Type exercise 1 to 10

Day 26
True/False Type exercise 11 to 20

Day 27
True/False Type exercise 21 to 30

Day 28
True/False Type exercise 31 to 37

Day 29
Concept Revision

Day 30
Formula Revision


Revision Facilitator


Try to recollect relevant points on the topic.

If required right click on the topic and click on open in a new window to read the relevant material.

Close the window and come back.





1 The definite integral

2 Evaluation of definite integrals

3 Geometric interpretation of definite integral

4 Evaluation of integrals by substitution

5 Properties of definite integrals

6 Integral function

7 Summation of series using definite integral as the limit of a sum

8 Gamma function






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Sunday, May 25, 2008

27 Definite Integrals - Revision points - 1

Properties of definite integrals

1. ∫ab f(x)dx = -∫ba f(x)dx



2. ∫ab f(x)dx = ∫ac f(x)dx + ∫cb f(x)dx


3. ∫0a f(x)dx = ∫0a f(a-x)dx

4. If f(-x) = f(x) (means f is an even function), then
-aa f(x)dx = 2∫0a f(x)dx

5. If f(-x) = -f(x) (means f is an odd function), then
-aa f(x)dx = 0

6. ∫0af(x)dx = ∫0af(a-x)dx and
abf(x)dx = ∫abf(a+b-x)dx

7. ∫0af(x)dx = ∫0a/2f(x)dx+∫0a/2f(a-x)dx

Due to the above relation

0af(x)dx = 0 if f(a-x) = -f(x)
0af(x)dx = 2∫0a/2f(x)dx if f(a-x) = f(x)

8. If f is continuous on [a,b], then the integral function defined by g(x) = ∫axf(t)dt for x Є [a,b]is derivable on [a,b], and g'(x) = f(x) for x Є [a,b].


9. If f(x0 is periodic with period T then

abf(x)dx = ∫a+nTb+nTf(x)dx, where n is an integer.

In particular

0nTf(x)dx = n∫0Tf(x)dx






If m and M are the smallest and greatest values of a function f(x) on an interval [a,b], then m(b-a)≤∫abf(x)dx≤M(b-a)

Sunday, April 27, 2008

Definite Integrals - Part 1

If F(x) is the antiderivative of a function f(x) continuous on (a,b)which means F'(x) = f(x) (a
∫f(x)dx {from a to b} = F(x) from a to b = F(b) - F(a)


Definite integral - Geometrical interpretation

the definite integral represents the algebraic sum of the areas of the figures bounded by

the graph of the function y = f(x)
the x axis
the straight line x =a and x = b.

if the curve goes above and below the x axis in the interval a to b, the areas of above the x axis enter this sum with a plus sign, while those below the x axis enter it with a minus sign.


Good online material

http://tutorial.math.lamar.edu/Classes/CalcI/DefnofDefiniteIntegral.aspx

Monday, October 22, 2007

Study Guide Ch.26. DEFINITE INTEGRALS

JEE Syllabus

definite integrals and their properties, application of the Fundamental Theorem of Integral Calculus.
Integration by parts, integration by the methods of substitution and partial fractions, application of definite integrals to the determination of areas involving simple curves.
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JEE question
If f″(x) = − f(x) and g(x) = f′(x) and F(x) = [f(x/2)]^2 + [g(x/2)]^2 and given that F(5) = 5 then F(10) is equal to

(A) 5
(B) 10
(C) 0
(D) 15

answer A
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