Let f(x) = (4x³ + x² + 4x + 2) / (x² + 1). Use long division to show that f(x) = 4x + 1 + 1 / (x² + 1) and use this result to evaluate ∫f(x) dx.
Table of contents
- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
- 8. Definite Integrals4h 44m
- 9. Graphical Applications of Integrals2h 27m
- 10. Physics Applications of Integrals 3h 16m
- 11. Integrals of Inverse, Exponential, & Logarithmic Functions2h 34m
- 12. Techniques of Integration7h 39m
- 13. Intro to Differential Equations2h 55m
- 14. Sequences & Series5h 36m
- 15. Power Series2h 19m
- 16. Parametric Equations & Polar Coordinates7h 58m
7. Antiderivatives & Indefinite Integrals
Indefinite Integrals
Problem 8.1.38
Textbook Question
7–64. Integration review Evaluate the following integrals.
38. ∫ x / (x⁴ + 2x² + 1) dx

1
Step 1: Observe the integrand ∫ x / (x⁴ + 2x² + 1) dx. Notice that the denominator can be factored. Rewrite the denominator as (x² + 1)², since x⁴ + 2x² + 1 is a perfect square trinomial.
Step 2: Substitute u = x² + 1 to simplify the integral. Compute the derivative of u with respect to x: du/dx = 2x, which implies du = 2x dx.
Step 3: Rewrite the integral in terms of u. Substitute x dx with (1/2) du, and the denominator becomes u². The integral now becomes (1/2) ∫ 1/u² du.
Step 4: Apply the power rule for integration to ∫ 1/u² du. Recall that ∫ u⁻² du = -u⁻¹ + C, where C is the constant of integration.
Step 5: Substitute back u = x² + 1 into the result to express the solution in terms of x. The final answer will be in the form of -1/(x² + 1) + C.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Integration Techniques
Integration techniques are methods used to find the integral of a function. Common techniques include substitution, integration by parts, and partial fraction decomposition. Understanding these methods is crucial for evaluating more complex integrals, such as the one presented in the question.
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Polynomial Functions
Polynomial functions are expressions that involve variables raised to whole number powers. In the integral ∫ x / (x⁴ + 2x² + 1) dx, the denominator is a polynomial of degree four. Recognizing the structure of polynomial functions helps in simplifying the integral and determining appropriate integration techniques.
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Rational Functions
Rational functions are ratios of two polynomial functions. The integral in the question involves a rational function, which can often be simplified or decomposed for easier integration. Understanding how to manipulate rational functions is essential for effectively evaluating integrals like the one given.
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