Basics of Integral in Calculus: Types, Methods, & Calculations

In mathematics, the integral is a fundamental concept in calculus that represents the accumulation or total of a quantity over a certain interval. It provides a powerful tool for calculating areas, finding volumes, measuring accumulated quantities, and solving a wide range of mathematical and scientific problems.

The integral is a mathematical concept that represents accumulation and provides a fundamental tool in calculus for calculating areas, measuring quantities, and solving problems by capturing the notion of accumulation and providing a powerful tool for calculations.

In this article, we will discuss the integral definition, a short introduction to integral, Types of integral, and methods of integration. Also, the integral will be explained with the help of detailed examples.

Integral in Calculus

Integration in mathematics is the process of finding the antiderivative of a function or calculating the accumulated value of a quantity over a given interval.

In mathematics, an integral is a fundamental concept in calculus that represents the accumulation or total of a quantity over a certain interval. It is used to compute areas, find volumes, measure accumulated quantities, and solve various mathematical and scientific problems.

Types of integral

Two types of integration in calculus

• Definite integral
• Indefinite integral

Definite integral

The definite integral is a representation of the whole value of a function f(x) over the range [a, b]. It calculates the net area between the graph of the function and the x-axis within that interval. We may put them in this form mathematically by using the definite integral.

ab f(x) dx = F(b) – F(a)

• where f(x) is the integrand
•  Here dx indicates the variable integration.
• [a, b] represents the interval of integration. Geometrically, it represents the area bounded by the function’s curve, the x-axis, and the vertical lines x = a and x = b.

Definite integrals can be used to calculate the area beneath, above, and between curves. If the supplied function is strictly positive in the given interval, the area between the curve and the x-axis equals the definite integral of the function. A negative function’s area is equal to the definite integral multiplied by -1. Antiderivative is another term for definite integrals.

Indefinite integral

The indefinite integral of “f” with respect to x is the collection of all antiderivative of f and is defined by

∫f(x) dx = F(x) + C

• where f(x) is integrand
• Here dx indicates the variable integration.

The family of functions represented by the indefinite integral has a specific derivative. In essence, it is distinction done backward. Unlike the definite integral, it does not have specified limits of integration and includes an arbitrary constant of integration (often denoted as + C).

The indefinite integral allows us to find the general solution to differential equations and provides a powerful tool for evaluating functions, determining areas under curves, and solving a variety of problems in mathematics, physics, engineering, and other fields.

Integration Methods:

Several methods of integration can be used to find antiderivative and evaluate definite integrals. Here are some commonly used methods:

• Power Rule:

If function is given in this form xn the power rule is used to find the integration of this type of function, where n is any real number except -1. The power rule states that:

∫xn dx = (1 / (n + 1)) × x(n + 1) + C

This rule allows you to find the antiderivative of polynomial functions.

• Substitution:

The method of substitution is used to simplify integrals by making a substitution for a variable. If u = g(x) is a differentiable function, then the substitution can be made to transform the integral into a simpler form. There are following steps of substitution are:

1. Substitute u = g(x), and rewrite the integral in terms of u.
2. To distinguish between u and x, locate du.
3. Substitute du for the appropriate expression involving dx.
4.  Calculate the integral that results in terms of u.
5. Substitute back in terms of x, if necessary.

When the function is composite functions these all method is useful for finding integration.

• By Parts Integration:

You can integrate the result of two functions using the integration-by-parts technique. Using the product rule for differentiation, and component integration. The formula for integration by components is.

∫u × v’ dx = u × v – ∫v × u’ dx

In this method, we choose randomly one function for differentiation and another for integration. This technique is helpful when the integral involves a product of functions, such as trigonometric functions multiplied by polynomials.

• Substitution of Trigonometric:

Trigonometric substitution is a technique used to simplify integrals involving radical expressions, especially when they contain expressions of the form √(a2 – x2), √(x2 + a2), or √(x2 – a2). By substituting specific trigonometric functions, you can transform the integral into a more manageable form.

• Special Integrals:

Certain integrals have special forms and can be directly evaluated. These include trigonometric integrals, exponential integrals, logarithmic integrals, and more. Memorizing these special forms can be useful in simplifying calculations.

How to Calculate Integral Calculus Problems?

The calculations involved in integral calculus problems can be rather lengthy. However, you can take assistance from an integral calculator to obtain step-by-step solutions for any integral problem within a fraction of a second.

Below are some solved examples to find integral of the functions manually.

Example 1:

∫ (5x2 -2x+1) dx=?

Solution:

Given function

∫ (5x2 -2x+1) dx=?

We can find the step-by-step integration with respect to x.

Step 1: Apply the integration of all given functions and take the linear function out of the integration.

∫ (5x2 -2x+1) dx=5∫ x2 dx-2∫x dx+∫1dx                                            (1)

Step 2: solve all given functions separately and put the answer value in the above function.

5∫ x2 dx

Solve by using the power rule

5 ∫ x2 dx = 5x3/3

= 5x3/3

2∫x dx

solve all given functions separately and put the answer value in the above function.

2 ∫ x dx = 2x2/2 + C

= x2 + c

∫1dx

Solve function by using constant rule

∫1dx = x + C

Step 3: Put all step two values in equation 1. We get

5∫ x2 dx – 2∫ x dx + ∫ 1 dx = 5x3/3 + x2+ x + C

Example 2:

∫ (sin(x) – cos(x) – 5) =?

Solution

Given data

sin(x)-cos(x)-5                             (A)

we can find the integration of the given question in a step-by-step solution

To find the integral of the function ∫ (sin(x) – cos(x) – 5) dx, we can integrate each term separately. Here are the step-by-step calculations:

Step 1: Integral of sin(x):

∫ sin(x) dx = -cos(x) + C1, where C1 is the constant of integration.

Step 2: Integral of cos(x):

∫ cos(x) dx = sin(x) + C2, where C2 is another constant of integration.

Step 3: Integral of 5:

∫ 5 dx = 5x + C3, where C3 is another constant of integration.

Putting it all in equation (A)

∫ (sin(x) – cos(x) – 5) dx = (-cos(x) + C1) – (sin(x) + C2) – (5x + C3)

Simplifying this expression, we can combine the constants of integration:

= -cos(x) – sin(x) – 5x + (C1 – C2 – C3)

Simplify the function.

∫ (sin(x) – cos(x) – 5) dx = -cos(x) – sin(x) – 5x + C, Also, we can write the C = C1 – C2 – C3 because the all represent the constant of integration.

Question 1:

How is the integral related to the derivative?

Derivative and integration are opposite each other. The derivative measures the rate of change of a function, while the integral measures the accumulation of a quantity over an interval. If we take any function integration, they give the original function.

Question 2:

Can all functions be integrated?

Not all functions can be integrated in terms of elementary functions (polynomials, exponentials, logarithms, trigonometric functions). Some functions have integrals that cannot be expressed in terms of elementary functions and require specialized techniques or numerical methods for approximation.

Question 3:

What is the meaning of integration geometrical representation?