Lesson
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💻 Integration

Integration.

This lesson covers core applied mathematics concepts and their agricultural applications for BSc Agriculture learners.


MATHS :: Lecture 10 ::INTEGRATION

Integration is a process, which is a inverse of differentiation. As the symbol lec10_clip_image002.gif represents differentiation with respect to x, the symbol lec10_clip_image004.gif stands for integration with respect to x.lec10_clip_image006.gif

Definition

If lec10_clip_image008.gif then f(x) is called the integral of F(x) denoted by lec10_clip_image010.gif. This can be read it as integral of F(x) with respect to x is f(x) + c where c is an arbitrary constant. The integral lec10_clip_image012.gif is known as Indefinite integral and the function F(x) as integrand.

Integration by parts Examples I

Integration by parts Examples II

Integration by parts Examples III

Formula on integration

1).lec10_clip_image014.gif +c ( n ¹-1)

2).lec10_clip_image016.gif +c

3).lec10_clip_image018.gif = x+c

4).lec10_clip_image020.gif +c

5).lec10_clip_image022.gif dx = ex +c

6).lec10_clip_image024.giflec10_clip_image026.gif

7).lec10_clip_image028.gif

8).lec10_clip_image030.gif = c x + d

9).lec10_clip_image032.gif +c

10).lec10_clip_image034.gif +c

11).lec10_clip_image036.gif +c

12).lec10_clip_image038.gif +c

13).lec10_clip_image040.gif

14).lec10_clip_image042.gif

13).lec10_clip_image044.gif +c

14).lec10_clip_image046.gif +c

15).lec10_clip_image048.gif +c

16).lec10_clip_image050.gif

Definite integral

If f(x) is indefinite integral of F(x) with respect to x then the Integral lec10_clip_image052.gif is called definite integral of F(x) with respect to x from x = a to x = b. Here a is called the Lower limit and b is called the Upper limit of the integral. lec10_clip_image052_0000.gif = lec10_clip_image054.gif = f(Upper limit ) - f(Lower limit) = f(b) - f(a)

Note

While evaluating a definite integral no constant of integration is to be added. That is a definite integral has a definite value.

Method of substitution

Method –1

Formulae for the functions involving (ax + b)

Consider the integral I = lec10_clip_image056.gif-------------(1) Where a and b are constants Put a x + b = y Differentiating with respect to x a dx + 0 = dy lec10_clip_image058.gif Substituting in (1) I = lec10_clip_image060.gif+c =lec10_clip_image062.gif+c =lec10_clip_image064.gif+c =lec10_clip_image066.gif+ c Similarly this method can be applied for other formulae also.

Method II

Integrals of the functions of the form

lec10_clip_image068.gif put lec10_clip_image070.gif=y, lec10_clip_image072.gif lec10_clip_image074.gif Substituting we get I =lec10_clip_image076.gif and this can be integrated.

Method –III

Integrals of function of the typelec10_clip_image002_0000.gif when n ¹ -1, put f(x) = y then lec10_clip_image004_0000.gif \ lec10_clip_image002_0001.gif=lec10_clip_image006_0000.gif = lec10_clip_image008_0000.gif = lec10_clip_image010_0000.gif when n= -1, the integral reduces to lec10_clip_image012_0000.gif putting y = f(x) then dy = f1(x) dx !lec10_clip_image014_0000.gif=log f(x)

Method IV

Method of Partial Fractions

Integrals of the formlec10_clip_image016_0000.gif

Case.1

If denominator can be factorized into linear factors then we write the integrand as the sum or difference of two linear factors of the form lec10_clip_image018_0000.gif

Case-2

In the given integral lec10_clip_image016_0001.gif the denominator ax2 + bx + c can not be factorized into linear factors, then express ax2 + bx + c as the sum or difference of two perfect squares and then apply the formulae

lec10_clip_image020_0000.gif

lec10_clip_image022_0000.gif

lec10_clip_image024_0000.gif

Integrals of the formlec10_clip_image026_0000.gif

Write denominator as the sum or difference of two perfect squares

lec10_clip_image026_0001.gif = lec10_clip_image028_0000.giforlec10_clip_image030_0000.gif orlec10_clip_image032_0000.gif

and then apply the formula

lec10_clip_image028_0001.gif = log(x+ lec10_clip_image034_0000.gif

lec10_clip_image030_0001.gif = log(x+ lec10_clip_image036_0000.gif

lec10_clip_image032_0001.gif = lec10_clip_image038_0000.gif

Integration by parts

If the given integral is of the form lec10_clip_image040_0000.gif then this can not be solved by any of techniques studied so far. To solve this integral we first take the product rule on differentiation lec10_clip_image042_0000.gif=ulec10_clip_image044_0000.gif +v lec10_clip_image046_0000.gif Integrating both sides we get lec10_clip_image048_0000.giflec10_clip_image042_0001.gifdx= lec10_clip_image048_0001.gif( ulec10_clip_image044_0001.gif +v lec10_clip_image046_0001.gif)dx then we have u v=lec10_clip_image051.gif+lec10_clip_image040_0001.gif re arranging the terms we get lec10_clip_image040_0002.gif = uv-lec10_clip_image051_0000.gif This formula is known as integration by parts formula Select the functions u and dv appropriately in such a way that integrallec10_clip_image051_0001.gif can be more easily integrable than the given integral

Application of integration The area bounded by the function y=f(x), x=axis and the ordinates at x=a x=b is given by lec10_clip_image053.gif

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Summary Cheat Sheet

  • Focus on core formulas, definitions, and solved patterns from this lesson.
  • Practice stepwise derivations and numerical substitutions carefully.
  • Connect each concept to practical agricultural problem-solving contexts.

References

1 source

Primary classroom notes and standard BSc Agriculture applied mathematics references.

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