Chapter 7: Problem 20
Evaluate each integral. \(\int \frac{\sin \sqrt{x}}{\sqrt{x}} d x\)
Short Answer
Expert verified
The integral evaluates to \(-2\cos(\sqrt{x}) + C\).
Step by step solution
01
Identify the Substitution
To simplify the integral, we need a substitution. Notice that the sine function's argument, \( \sqrt{x} \), suggests using a substitution related to \( \sqrt{x} \). Let's set \( u = \sqrt{x} \). Differentiating both sides, we get \( du = \frac{1}{2\sqrt{x}} \, dx \). Rearranging gives \( dx = 2u \, du \).
02
Substitute and Simplify the Integral
Substitute \( u = \sqrt{x} \) and \( dx = 2u \, du \) into the integral: \[\int \frac{\sin \sqrt{x}}{\sqrt{x}} \, dx = \int \frac{\sin u}{u} (2u) \, du = 2 \int \sin u \, du\] Now, the integral is simplified to \( 2 \int \sin u \, du \).
03
Integrate with Respect to \( u \)
Now, integrate \( 2 \int \sin u \, du \):\[2 \int \sin u \, du = 2(-\cos u) + C = -2\cos u + C\]We have integrated \( \sin u \) to get \( -\cos u \), then multiplied by 2.
04
Back-Substitute to Original Variable
Replace \( u \) with \( \sqrt{x} \) in the result of the integration:\[-2\cos u + C = -2\cos(\sqrt{x}) + C\]This is the solution to the original integral.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Substitution Method
The substitution method is a fundamental tool in calculus that simplifies complex integrals into more manageable ones. It is particularly useful when dealing with composite functions such as trigonometric, exponential, or logarithmic functions.
- When using substitution, we identify a part of the integral that can be replaced with a single variable.
- In the context of the exercise, we substitute the inner function, which is \( u = \sqrt{x} \).
- This changes the original differential \( dx \) into a simpler form, \( dx = 2u \, du \), making the integral much easier to solve.
Definite Integrals
While this exercise focuses on indefinite integrals, definite integrals involve finding the area under a curve between two specific limits. Despite their differences, understanding indefinite integrals is crucial for mastering definite integrals.
- A definite integral has the form \( \int_{a}^{b} f(x) \, dx \), where \( a \) and \( b \) are the integration limits.
- The substitution method can still be applied, but one must also adjust the limits of integration according to the substitution.
Trigonometric Integrals
Trigonometric integrals are a specific class of integrals involving trigonometric functions like sine, cosine, and tangent. They appear frequently in calculus problems due to their periodic nature and broad applicability.
- The integral in the exercise is a trigonometric integral because of the presence of the \( \sin(u) \) function.
- Recognizing trigonometric functions allows us to apply known integration formulas such as \( \int \sin u \, du = -\cos u + C \).
- Understanding these integrals enables us to find areas, solve differential equations, and model wave functions.