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Indefinite Integrals Formula, Definition, Properties, Examples

Indefinite Integral: In this case, we will focus on the indefinite integral, which deals with finding antiderivatives or the general forms of functions that have a given derivative.
authorImageGirijesh Singh4 Oct, 2023
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Indefinite Integrals Formula

In calculus, two fundamental processes are differentiation and integration. Differentiation involves finding the derivative of a function, while integration is the inverse process of differentiation. In this discussion, we will focus on an essential concept in integration known as "integrals."

Consider a function f that is differentiable over an interval I, meaning its derivative f' exists at every point within I. This leads to a fundamental question: Can we determine the original function that would yield the given f' at each point? Functions capable of producing f' as their derivative are known as antiderivatives or primitives. The mathematical formula that provides all these antiderivatives is termed the indefinite integral of the function, and the process of finding these antiderivatives is called integration. Integrals are generally categorized into two main types: Definite Integral: This type of integral is used to calculate the accumulated effect of a function over a specific interval. Indefinite Integral: In this case, we will focus on the indefinite integral, which deals with finding antiderivatives or the general forms of functions that have a given derivative. Let's delve deeper into the concept of the indefinite integral, its definition, and properties.

Indefinite Integrals Definition

An indefinite integral is an integral that does not have specific upper and lower limits. In mathematical terms, if F(x) represents any antiderivative of the function f(x), then the most general antiderivative of f(x) is referred to as an indefinite integral and is denoted as: ∫f(x) dx = F(x) + C Here are some symbols, terms, and phrases along with their meanings for better understanding: ∫: The integral symbol represents the process of integration. f(x): This represents the function for which we want to find the antiderivative. dx: It indicates the variable of integration, representing the independent variable. F(x): This represents any antiderivative of the function f(x). C: The constant "C" is known as the constant of integration and can take any real value. It accounts for the fact that there can be multiple antiderivatives of a given function. This notation and concept of indefinite integrals are fundamental in calculus and are used extensively for finding antiderivatives of various functions.
Symbols/Terms/Phrases Meaning
∫ f(x) dx Integral of f with respect to x
f(x) in  ∫ f(x) dx Integrand
x in ∫ f(x) dx Variable of integration
An integral of f A function F such that F′(x) = f (x)
Integration The process of finding the integral
Constant of Integration Any real number C, considered as constant function

Also Check - Derivatives Formula

Antiderivatives or integrals of functions are not unique. There are infinitely many antiderivatives for certain functions, and they can be obtained by choosing an arbitrary constant "C" from the set of real numbers. For this reason, "C" is commonly referred to as an arbitrary constant. It serves as the parameter that allows us to obtain different antiderivatives (or integrals) of the same given function. This arbitrary constant accounts for the various possible forms of antiderivatives and is a fundamental concept in indefinite integration.

Indefinite Properties

Property 1: The process of differentiation and integration are inverses of each other in the sense of the following results: 26Indefinite Properties where C is any arbitrary constant. Let us now prove this statement. Proof: Consider a function f such that its anti-derivative is given by F, i.e. 27Indefinite Properties The derivative of a function f in x is given as f’(x), so we get; 28Indefinite Properties Hence, proved. Property 2: Two indefinite integrals with the same derivative lead to the same family of curves, and so they are equivalent. Proof: Let f and g be two functions such that 29Indefinite Properties where C is any real number. From this equation, we can say that the family of the curves of [ ∫ f(x)dx + C3, C3 ∈ R] and [ ∫ g(x)dx + C2, C2 ∈ R] are the same. Therefore, we cay say that, ∫ f(x)dx = ∫ g(x)dx Property 3: The integral of the sum of two functions is equal to the sum of integrals of the given functions, i.e., 30Indefinite Properties Proof: From property 1 we can say that 31Indefinite Properties Also, 32Indefinite Properties

Property 5:

For a finite number of functions f1, f2…. fn and the real numbers p1, p2…pn, ∫[p1f1(x) + p2f2(x)….+pnfn(x) ]dx = p1∫f1(x)dx +  p2∫f2(x)dx + ….. +  pn∫fn(x)dx Indefinite Integral Formulas The list of indefinite integral formulas are
  • ∫ 1 dx = x + C
  • ∫ a dx = ax + C
  • ∫ xn dx = ((xn+1)/(n+1)) + C ; n ≠ 1
  • ∫ sin x dx = – cos x + C
  • ∫ cos x dx = sin x + C
  • ∫ sec2x dx = tan x + C
  • ∫ cosec2x dx = -cot x + C
  • ∫ sec x tan x dx = sec x + C
  • ∫ cosec x cot x dx = -cosec x + C
  • ∫ (1/x) dx = ln |x| + C
  • ∫ ex dx = ex + C
  • ∫ ax dx = (ax/ln a) + C ; a > 0,  a ≠ 1

Also Check - Differential Equation Formula

Indefinite Integrals Examples

Example 1:

Let's evaluate the given indefinite integral problem: ∫(6x^5 - 18x^2 + 7) dx. Solution: Given, ∫(6x^5 - 18x^2 + 7) dx Integrate the given function: ∫(6x^5 - 18x^2 + 7) dx = (6/6)x^6 - (18/3)x^3 + 7x + C After simplification, we get the solution: ∫(6x^5 - 18x^2 + 7) dx = x^6 - 6x^3 + 7x + C

Example 2:

Evaluate f(x) given that f'(x) = 6x^8 - 20x^4 + x^2 + 9. Solution: Given, f'(x) = 6x^8 - 20x^4 + x^2 + 9 We know that the inverse process of differentiation is integration: f(x) = ∫f'(x) dx = ∫(6x^8 - 20x^4 + x^2 + 9) dx After integration, we obtain: f(x) = (2/3)x^9 - 4x^5 + (1/3)x^3 + 9x + C

Also Check - Vector Formula

Indefinite Integral vs Definite Integral

An indefinite integral is a mathematical function that represents the antiderivative of another function. It is typically denoted using the integral symbol, followed by a function expression, and then "dx" to indicate the variable of integration. The indefinite integral is a concise way to express the process of finding the antiderivative of a function. While the concept of indefinite integrals is similar to that of definite integrals, the two are distinct. In the context of a definite integral, specific upper and lower limits are defined to calculate the accumulated effect of a function over a specified interval. In contrast, an indefinite integral focuses on finding the general antiderivative of a function without specifying a particular interval. The difference between definite and indefinite integrals can be visually represented as shown in the figure below, highlighting their distinct characteristics and purposes.

Indefinite Integrals Formula FAQs

How do you find the indefinite integral?

To find the indefinite integral of a function, you perform the process of integration or antideriviation on the function f(x). This process can be represented as: ∫f(x) dx = F(x) + C, where C is an arbitrary constant. Suitable integration techniques and formulas are applied to obtain the antiderivative of the given function. The result of the indefinite integral is a function.

What does an indefinite integral represent?

The indefinite integral represents a family of functions, all of which have the same derivative as the original function f. It represents the set of antiderivatives of the given function.

Are indefinite integrals and antiderivatives the same?

Yes, indefinite integrals and antiderivatives refer to the same concept. When you find the indefinite integral of a function, you are essentially finding its antiderivative, which is a function that, when differentiated, gives the original function.

Do definite integrals have C?

No, definite integrals do not contain the constant "C" in their expressions. The "C" is only present in the result of an indefinite integral, representing the family of antiderivative functions.

What are the bounds of an indefinite integral?

There are no specific bounds for an indefinite integral. It deals with finding the general antiderivative of a function and does not involve specific upper and lower limits as seen in definite integrals.
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