Math Problem Statement

∫ (sqrt(x^2 - 1) / x) dx

Solution

The integral shown in the image is:

x21xdx\int \frac{\sqrt{x^2 - 1}}{x} \, dx

This is a standard integral and can be solved using a trigonometric substitution. Let's go through the steps to solve it.

Step-by-step solution:

  1. Substitute: Use the trigonometric identity x=sec(θ)x = \sec(\theta), which implies: dx=sec(θ)tan(θ)dθdx = \sec(\theta) \tan(\theta) \, d\theta and, x21=sec2(θ)1=tan(θ)\sqrt{x^2 - 1} = \sqrt{\sec^2(\theta) - 1} = \tan(\theta)

  2. Rewrite the integral: Substituting these values into the integral: x21xdx=tan(θ)sec(θ)sec(θ)tan(θ)dθ\int \frac{\sqrt{x^2 - 1}}{x} \, dx = \int \frac{\tan(\theta)}{\sec(\theta)} \sec(\theta) \tan(\theta) \, d\theta

    This simplifies to: tan2(θ)dθ\int \tan^2(\theta) \, d\theta

  3. Use the trigonometric identity: Recall that tan2(θ)=sec2(θ)1\tan^2(\theta) = \sec^2(\theta) - 1. So the integral becomes: (sec2(θ)1)dθ\int (\sec^2(\theta) - 1) \, d\theta

  4. Integrate: sec2(θ)dθ1dθ=tan(θ)θ+C\int \sec^2(\theta) \, d\theta - \int 1 \, d\theta = \tan(\theta) - \theta + C

  5. Substitute back θ\theta: Since x=sec(θ)x = \sec(\theta), we know: tan(θ)=x21\tan(\theta) = \sqrt{x^2 - 1} and θ=sec1(x)\theta = \sec^{-1}(x)

    Therefore, the solution is: x21sec1(x)+C\sqrt{x^2 - 1} - \sec^{-1}(x) + C

Final Answer:

x21xdx=x21sec1(x)+C\int \frac{\sqrt{x^2 - 1}}{x} \, dx = \sqrt{x^2 - 1} - \sec^{-1}(x) + C

Would you like further details or explanations on any of the steps?


Here are 5 related questions that expand on this topic:

  1. How can other trigonometric substitutions be used for different types of integrals?
  2. What is the significance of using trigonometric identities in solving integrals?
  3. How can the inverse secant function be interpreted geometrically?
  4. What are other methods to solve integrals involving square roots of quadratic expressions?
  5. How does the method of partial fractions apply to integrals with rational expressions?

Tip: Always consider using trigonometric identities when encountering square roots involving quadratic expressions in integrals. They often simplify the problem significantly.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Trigonometric Substitution
Inverse Trigonometric Functions

Formulas

∫ (sqrt(x^2 - 1) / x) dx = sqrt(x^2 - 1) - sec^(-1)(x) + C
Trigonometric substitution: x = sec(θ), dx = sec(θ) tan(θ) dθ
Identity: tan^2(θ) = sec^2(θ) - 1

Theorems

Trigonometric Identities
Inverse Secant Function

Suitable Grade Level

College Calculus