How to Solve the Indefinite Integral with Trigonometric Substitution?

In summary, an indefinite integral is the antiderivative of a function and is denoted by the symbol ∫. It differs from a definite integral in that it does not have specific limits of integration and gives a general function rather than a numerical value. To find an indefinite integral, the antiderivative of the function must be determined using integration techniques. Indefinite integrals are important in science, particularly in fields such as physics and engineering, as they are used to solve problems involving rates of change. However, not all functions have an indefinite integral, as they must be continuous and differentiable in order to have one.
  • #1
chimychang
5
0

Homework Statement




[tex] \int{ x^3 \sqrt{(36-x^2)}dx} [/tex]

Homework Equations





The Attempt at a Solution



I tried using trig substitution but got [tex] 7776\int{cos^3(\theta)-cos^5(\theta)d\theta} [/tex] which seems completely wrong



[tex]6cos(\theta)=x
[/tex]
[tex]6sin(\theta)d\theta=dx
[/tex]
[tex]6sin(\theta)=\sqrt{36-x^2}
[/tex]

[tex] \int{ (6cos(\theta))^36sin(\theta)6sin(\theta)d\theta [/tex]
 
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  • #2
You have an odd number of "x"s outside the square root so try this: Write the integral as [itex]\int x^2\sqrt{36- x^2}(x dx)[/itex] and let u= 36- x2. Then du= 2x dx so x dx= (1/2)du and [itex]x^2= 36- u[/itex].
 

What is an indefinite integral?

An indefinite integral is a mathematical concept that represents the antiderivative of a given function. It is used to find the original function from its derivative, and is denoted by the symbol ∫.

What is the difference between an indefinite integral and a definite integral?

The main difference between an indefinite integral and a definite integral is that a definite integral has specific limits of integration, while an indefinite integral does not. This means that a definite integral will give a numerical value, while an indefinite integral will give a general function.

How do you find the indefinite integral of a function?

To find the indefinite integral of a function, you must first determine the antiderivative of the function. This can be done using various integration techniques, such as integration by substitution, integration by parts, or using integral tables. Once the antiderivative is found, the indefinite integral can be written with the addition of a constant of integration.

What is the importance of indefinite integrals in science?

Indefinite integrals are an essential tool in mathematics and science, particularly in fields such as physics and engineering. They are used to solve problems involving rates of change, such as velocity and acceleration. Indefinite integrals also have applications in statistics, economics, and other areas of science.

Can all functions have an indefinite integral?

No, not all functions have an indefinite integral. A function must be continuous and differentiable in order to have an indefinite integral. Functions with discontinuities or sharp corners, such as the absolute value function, do not have an indefinite integral. Additionally, some functions may have an indefinite integral that cannot be expressed in terms of elementary functions.

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