Chapter 5: Problem 6
Evaluate the indefinite integrals in Exercises \(1-16\) by using the given substitutions to reduce the integrals to standard form. $$ \int \frac{(1+\sqrt{x})^{1 / 3}}{\sqrt{x}} d x, u=1+\sqrt{x} $$
Short Answer
Expert verified
The indefinite integral is \( \frac{3}{2}(1+\sqrt{x})^{4/3} + C \).
Step by step solution
01
Substitute and Express in terms of u
Given the substitution \(u=1+\sqrt{x}\), we need to express \(\sqrt{x}\) in terms of \(u\). Since \(u = 1 + \sqrt{x}\), it follows that \(\sqrt{x} = u - 1\). Also, differentiate both sides with respect to \(x\) to find \(dx\) in terms of \(du\). We have \(\frac{d}{dx}(\sqrt{x}) = \frac{1}{2\sqrt{x}} = \frac{1}{2(u-1)}.\) Thus, \(dx = 2(u-1)\ du.\)
02
Substitute and Simplify the Integral
Replace \(\sqrt{x}\), the numerator, and \(dx\) in the integral using the substitutions. This gives us: \[\int \frac{(1+\sqrt{x})^{1/3}}{\sqrt{x}}\, dx = \int \frac{u^{1/3}}{u-1}\ (2(u-1)du). \]This simplifies to:\[2 \int u^{1/3} du.\]
03
Evaluate the Integral
Now, integrate \(2 \int u^{1/3} du\) which simplifies to:\[2 \int u^{1/3} du = 2 \cdot \left[\frac{u^{4/3}}{4/3}\right] + C.\]Simplifying gives:\[\frac{3}{2} u^{4/3} + C.\]
04
Substitute Back in terms of x
Recall \(u=1+\sqrt{x}\). Substitute this back into the expression to return to terms of \(x\):\[\frac{3}{2}(1+\sqrt{x})^{4/3} + C.\]
05
Write the Final Answer
The indefinite integral is:\[\int \frac{(1+\sqrt{x})^{1/3}}{\sqrt{x}}\, dx = \frac{3}{2}(1+\sqrt{x})^{4/3} + C.\] Where \(C\) is the constant of integration.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Indefinite Integrals
In calculus, indefinite integrals are fundamental to understanding the area under a curve without specifying limits of integration. When you compute an indefinite integral, you're essentially finding a family of functions whose derivative gives back the original function from which you started. This process is often referred to as 'anti-differentiation.' An important aspect to remember is that indefinite integrals include a constant of integration, often represented as "C," since the derivative of any constant is zero.
The notation for an indefinite integral is typically expressed as:
The notation for an indefinite integral is typically expressed as:
- \( \int f(x) \, dx \)
Integration Techniques
When tackling integration, using the right technique is crucial. There are various methods to integrate functions, but the goal is always the same: simplify the integral into a form that is easier to evaluate. Some main techniques include:
Trying different techniques is often necessary to recognize patterns within the function to find the simplest path to the solution.
- Substitution Method
- Integration by Parts
- Trigonometric Integration
- Partial Fraction Decomposition
Trying different techniques is often necessary to recognize patterns within the function to find the simplest path to the solution.
Substitution Method
The substitution method, a powerful tool in calculus, simplifies complex integrals by changing the variable of integration. This technique leverages a substitution to transform the integral into a more manageable form. Here's how it often works:
- Identify a portion of the integrand (the function inside the integral) that can be replaced with a new variable, \(u\).
- Express all original variables and \(dx\) in terms of \(u\) and \(du\).
- Substitute back into the integral, simplifying wherever possible.
- Complete the integration with respect to \(u\), and finally substitute back the original variable to obtain the result.