Methods of Integration

• In Mathematics, when we cannot perform general addition operations, we use integration to add values on a large scale.

• There are various methods in mathematics to integrate functions.

•  Integration and differentiation are also a pair of inverse functions similar to  addition- subtraction, and multiplication-division. 

• The process of finding functions whose derivative is given is named anti-differentiation or integration. 

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Here’s What Integration is!

Points to Remember:

Types of Integration Maths or the Integration Techniques-

Here’s a list of Integration Methods –

1. Integration by Substitution

2. Integration by Parts

3. Integration by Partial Fraction

4. Integration of Some particular fraction

5. Integration Using Trigonometric Identities

For better understanding here’s what each method is!

1. Integration by Substitution -

• We can find the integration by introducing a new independent variable when it is difficult to find the integration of a function. 

• By changing the independent variable x to t, in a given form of integral function say

• (∫f(x))

• (∫f(x)), we can transform the integral.

Let’s substitute the value of independent x = g(t) in the integral function ∫f(x), 

We get, dx / dt = g’(t)

Or, dx = g’(t) • dt

Thus, from the above substitution ,we get,

I=∫f(x).dx=f(g(t).

g′(t)).dt

I=∫f(x).dx=f(g(t).g′(t)).dt

2. Integration by Parts –

• If the integrand function can be represented as a multiple of two or more functions, the integration of any given function can be done by using the Integration by Parts method.

• Let us take an integrand function that is equal to f(x)g(x).

• In mathematics, Integration by part uses the ILATE rule for selecting the first and second functions in this method.

• In mathematics, here’s how integration by parts is represented.

∫f(x).g(x).dx = f(x).∫g(x).dx – ∫(f′(x).∫g(x).dx).dx

Which can be further written as integral of the product of any two functions = (First function × Integral of the second function) – Integral of

(differentiation of the first function)×Integral Of The Second Function

(differentiation of the first function)×Integral Of The Second Function

3. Integration Using Trigonometric Identities –

• Trigonometric identities are used to simplify any integral function which consists of trigonometric functions.

• It simplifies the integral function so that it can be easily integrated.

• There are many trigonometric identities, a few are listed below!

Sin²x = \[\frac {(1-Cos 2x)}{2}\]

Cos²x = \[\frac {(1+ Cos 2x)}{2}\]  

4. Integration of Some Particular Function -

• Many other standard integrals can be integrated using some important integration formulas.

• Here are the six important formulas listed below - 

• ∫ dx/ (x² – a²) = ½  a log | (x – a) / (x + a) | + c

• ∫ dx/ (a² – x²) = ½ a log | (a + x) / (a – x) | + c

• ∫ dx / (x² + a²) = 1/a tan–1 (x/a) + c

• ∫ dx /√ (x² – a²) = log| x+√(x² – a²) | + c

• ∫ dx /√ (a² – x²) = sin–1 (xa) + c

• ∫ dx /√ (x² + a²) = log | x + √(x² + a²) | + c

Where, c = constant

5. Integration by Partial Fraction -

• The partial fraction method is the last method of integration class 12.

• In mathematics, rational numbers can be expressed in the form of

• p

• q

• pq
  where p and q are integers and where the value of the denominator q is not equal to zero.

• The ratio of two polynomials is known as a rational fraction and it can be expressed in the form of

• p(x)

• q(x)

• p(x)q(x)
  , where the value of p(x) should not be equal to zero.

• The two forms of partial fraction have been described below-

            Proper Partial function 

            Improper Partial function

• What is the proper partial function?

When the degree of the denominator is more than the degree of the numerator, the function is known as a proper partial function.

• What is an improper partial function?

When the degree of the denominator is less than the degree of the numerator then the fraction is known as improper partial function. Thus, the fraction can be simplified into parts and can be integrated easily.

Topics Covered in Methods of Integration: Definitions, Types, Examples

Integration is used to add large values in mathematics when the calculations cannot be performed on general operations. There are many methods of integration that are used specifically to solve complex mathematical operations. 

The different kinds of methods of integration are: -

• Integration by Parts.

• Method of Integration Using Partial Fractions.

• Integration by Substitution Method.

• Integration by Decomposition.

• Reverse Chain Rule.

• Integration Using Trigonometric Identities.

All methods of integration are important. Integration by parts is one of the best because it is used when a function that has to be integrated is written as a product of two or more. Integration by parts is also known as the product rule of integration and the UV method of integration. When you have to integrate rational functions, a method of integration using partial fractions is used. The reverse chain rule is also one of the easiest and most commonly used methods of integration.