Chapter 6: Problem 13
Find the indefinite integral. $$ \int \frac{x}{\sqrt[3]{x^{2}+1}} d x $$
Short Answer
Expert verified
\( \int \frac{x}{\sqrt[3]{x^{2}+1}} \, dx = \frac{3}{4}(x^{2}+1)^{2/3} + C \)
Step by step solution
01
Choose a Substitution
Let's choose a substitution to simplify this integral. We'll substitute: \[ u = x^{2} + 1 \] Then calculate the derivative of \( u \): \[ du = 2x \, dx \] So, we have \( x\,dx = \frac{1}{2} du \).
02
Substitute in the Integral
Using the substitution \( u = x^2 + 1 \), we rewrite the integral: \[ \int \frac{x}{\sqrt[3]{x^{2}+1}} \, dx = \int \frac{x}{\sqrt[3]{u}} \, dx \]Now, substituting for \( x \, dx \), we get:\[ \int \frac{1}{2} \cdot \frac{1}{u^{1/3}} \, du = \frac{1}{2} \int u^{-1/3} \, du \]
03
Integrate Using Power Rule
Now, apply the power rule of integration: \[ \int u^n \, du = \frac{u^{n+1}}{n+1} + C \]For our integral, \( n = -\frac{1}{3} \), so:\[ \frac{1}{2} \left( \frac{u^{2/3}}{2/3} \right) = \frac{3}{4} u^{2/3} + C \]
04
Substitute Back in Terms of x
Replace \( u \) with the original expression, \( x^{2} + 1 \):\[ \frac{3}{4} (x^{2} + 1)^{2/3} + C \]This is the indefinite integral in terms of \( x \), where \( C \) is the integration constant.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Substitution Method
The substitution method is a powerful technique used in calculus to simplify integrals that seem complex at first glance. The main idea is to substitute a part of the integrand with a variable that makes the integral easier to solve. This process involves a few steps: identify the part of the integrand to substitute, express the substitution in terms of a new variable, and then rewrite the differential accordingly.
For the given problem, the substitution method involves the expression:
For the given problem, the substitution method involves the expression:
- Determine the substitution: let \( u = x^2 + 1 \), as it appears in the denominator.
- Calculate the differential: the derivative of \( u \) is \( du = 2x \, dx \). Consequently, \( x \, dx = \frac{1}{2} du \), and this will replace \( x \, dx \) in the integral.
Integration Power Rule
The integration power rule is one of the fundamental tools in calculus, used to find the antiderivative of a function. It states that the integral of \( u^n \) with respect to \( u \) is \( \frac{u^{n+1}}{n+1} + C \), where \( n eq -1 \). This rule allows us to directly find the indefinite integral of polynomial expressions.
In the context of the exercise:
In the context of the exercise:
- Identify \( n = -\frac{1}{3} \) after substituting \( u = x^2 + 1 \).
- Apply the power rule: \( \int u^{-1/3} \, du = \frac{u^{2/3}}{2/3} + C \).
- Simplify further as \( \frac{3}{4} u^{2/3} + C \).
Calculus Problem Solving
Solving calculus problems often requires a multi-step approach where different techniques are used together, much like putting together pieces of a puzzle. For indefinite integrals, it's crucial to understand the function type and choose the appropriate method, such as substitution, integration by parts, or partial fractions.
In this exercise, problem-solving involves:
In this exercise, problem-solving involves:
- Using substitution to simplify the integral into a form where traditional techniques can be employed.
- Applying the integration power rule, a straightforward calculus formula, to integrate the expression.
- Back-substitute to revert to the original variable, yielding the solution in its initial terms.
- Include the integration constant \( C \), as indefinite integrals represent a family of functions.
Mathematical Constants
In calculus, mathematical constants like \( C \) play a pivotal role, especially in indefinite integrals. When integrating, we seek an antiderivative, which is not unique. Hence, we include \( C \), representing an infinite set of vertical shifts of the antiderivative curve.
In our solution:
In our solution:
- We find \( \frac{3}{4} (x^2+1)^{2/3} \) as a primary form of antiderivative.
- Without \( C \), the solution would appear overly specific and incorrectly imply a unique curve.
- \( C \) reflects our understanding that the indefinite integral accounts for all possible shifts, pinpointing the solution's flexibility.