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Unit 2: Indefinite Integrals: Antiderivatives

In integral calculus, indefinite integrals play a fundamental role in finding antiderivatives and understanding the accumulated change of a function over an interval. Let’s delve into the concept of indefinite integrals, their connection to antiderivatives, and how to utilize a table of indefinite integrals effectively for problem-solving.

  • What are Indefinite Integrals?

Indefinite integrals, denoted by [latex]\int f(x) dx[/latex], represent a family of functions rather than a single numerical value. They are expressed using the integral symbol without specified upper and lower limits. From a mathematical perspective, an indefinite integral represents all possible antiderivatives of a given function [latex]f(x)[/latex]. In simpler terms, it answers the question: “What function has a derivative equal to [latex]f(x)[/latex]?”  For instance, a set of functions, [latex]x^2-100, ..., x^2, ..., x^2+100[/latex]) all share the derivative [latex]2x[/latex], hence [latex]\int 2x dx=x^2+C[/latex] where C is any real number.

  • Relationship with Antiderivatives

Indefinite integrals are closely related to antiderivatives. An antiderivative of a function [latex]f(x)[/latex] is any function [latex]F(x)[/latex] whose derivative equals [latex]f(x)[/latex]. Therefore, an indefinite integral [latex]\int f(x) dx[/latex] represents the general antiderivative of [latex]f(x)[/latex]. Symbolically, if [latex]F(x)[/latex] is an antiderivative of f(x), then[latex]\int f(x) dx = F(x) + C[/latex], where [latex]C[/latex] is the constant of integration.

  • Table of Indefinite Integrals:

A table of indefinite integrals provides a comprehensive list of common functions and their corresponding antiderivatives. Some essential entries in this table include:

This table is a comparison table of derivatives and integrals

Practice Questions:

Evaluate the following indefinite integrals before referring to the video for comprehensive solutions.

Q1. [latex]\int e \,dx[/latex]

Q2. [latex]\int -4.1 \,dx[/latex]

Q3. [latex]\int 0 \,dx[/latex]

Q4. [latex]\int x^2 \,dx[/latex]

Q5. [latex]\int x^{2/3} \, dx[/latex]

Q6. [latex]\int x^{-\pi} \,dx[/latex]

Q7. [latex]\int \sqrt{x^3} \,dx[/latex]

Q8. [latex]\int \sqrt[5]{x^2} \,dx[/latex]

Q9. [latex]\int \frac{1}{x^2} \,dx[/latex]

Q10. [latex]\int \frac{1}{\sqrt[3]{x^2}} \,dx[/latex]

Q11. [latex]\int 5^t \,dt[/latex]

Q12. [latex]\int \sin\theta \,d\theta[/latex]

 

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