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Ch. 8 - Techniques of Integration
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077당신이 사용하는 게 아니라요?교과서 변경
8장, 문제 8.1.6

The integrals in Exercises 1–44 are in no particular order. Evaluate each integral using any algebraic method, trigonometric identity, or substitution you think is appropriate.
∫ dx / (x - √x)

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1
Start by rewriting the integral to make it easier to work with. Notice that the denominator is \(x - \sqrt{x}\). To simplify, let’s express everything in terms of \(\sqrt{x}\). Set \(t = \sqrt{x}\), which implies \(x = t^2\) and \(dx = 2t \, dt\).
Substitute \(x = t^2\) and \(dx = 2t \, dt\) into the integral. The integral becomes \(\int \frac{2t \, dt}{t^2 - t}\). Simplify the denominator: \(t^2 - t = t(t - 1)\), so the integral is \(\int \frac{2t}{t(t - 1)} \, dt\).
Simplify the integrand by canceling \(t\) in numerator and denominator, resulting in \(\int \frac{2}{t - 1} \, dt\). This is a simpler rational function integral.
Integrate \(\int \frac{2}{t - 1} \, dt\) by recognizing it as a standard form \(\int \frac{1}{u} \, du = \ln|u| + C\). Here, \(u = t - 1\), so the integral is \(2 \ln|t - 1| + C\).
Finally, substitute back \(t = \sqrt{x}\) to express the answer in terms of \(x\). The result is \(2 \ln|\sqrt{x} - 1| + C\).

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
2m

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Algebraic Manipulation

Algebraic manipulation involves rewriting expressions to simplify integrals. In this problem, expressing the denominator in terms of a single variable or factoring can make the integral easier to evaluate. For example, substituting √x with a new variable can transform the integral into a more manageable form.
추천 영상:
05:25
Determine Continuity Algebraically

Substitution Method

The substitution method replaces a complicated expression with a simpler variable to facilitate integration. Here, letting t = √x converts the integral into a rational function in terms of t, allowing easier integration. This technique is essential when dealing with roots or composite functions.
추천 영상:
07:33
Euler's Method

Integration of Rational Functions

Integrating rational functions often involves partial fraction decomposition or recognizing standard integral forms. After substitution, the integral becomes a rational function in t, which can be integrated by breaking it into simpler fractions or using known integral formulas.
추천 영상:
6:04
Intro to Rational Functions