Finding the integral of a function

In summary: In other words, it changes it to ln(u).In summary, the integral of the given function is simply the natural logarithm of the denominator, ln|x^3+2| + a constant of integration, since the numerator is the derivative of the denominator. Substitution is the easiest technique to use in this case.
  • #1
iaing94
11
0

Homework Statement


Hi, all I need to do is find the integral of a function, and I am struggling with where to begin with this particular expression.

Homework Equations



[itex]\int[(3x^2)/(x^3+ 2)]dx[/itex]

The Attempt at a Solution



Thats the problem, I am not sure where to start! I am sure it is something obvious I am missing.
Thanks

Homework Statement


Homework Equations


The Attempt at a Solution

 
Last edited:
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  • #2
I assume you mean [itex]\int[(3x^2)/(x^3+ 2)]dx[/itex].

Let [itex]u= x^3+ 2[/itex].
 
  • #3
Thanks for your quick reply. Sorry, that is exactly what I meant, I am not great with laying stuff out online.

Substituting was my first thought, however this question is part of a pre-test I am doing for homework, and there is a section on substituting later on in the paper, so I am guessing I'm not supposed to use that here. Is there another way doing it?
 
  • #4
For equations of this form, where the numerator is the derivative of the denominator, the integral is simply the natural logarithm of the denominator. So in this case it would be ln|x^3+2| + a constant of integration.
 
  • #5
iaing94 said:
Substituting was my first thought, however this question is part of a pre-test I am doing for homework, and there is a section on substituting later on in the paper, so I am guessing I'm not supposed to use that here. Is there another way doing it?
Substitution is probably the easiest technique, and the one that should be tried first. I can't think of any other way to do this problem.
 
  • #6
Jamo1991 said:
For equations of this form, where the numerator is the derivative of the denominator, the integral is simply the natural logarithm of the denominator. So in this case it would be ln|x^3+2| + a constant of integration.

I never knew that, that works every time? Care to explain how?
 
  • #7
Because of "substitution" whether you call it that or not! If your integral is of the form [itex]\int f'(x)/f(x)dx[/itex], let u= f(x), du= f'dx changes the integral to [itex]\int du/u[/itex].
 

Related to Finding the integral of a function

1. What is the purpose of finding the integral of a function?

The integral of a function is used to calculate the area under the curve of the function. It can also be used to find the total change in a quantity over a given interval.

2. How do you find the integral of a function?

The integral of a function can be found using integration techniques such as substitution, integration by parts, and trigonometric substitution. It can also be found using numerical methods such as the trapezoidal rule or Simpson's rule.

3. What is the difference between indefinite and definite integrals?

An indefinite integral does not have limits and is represented by the symbol ∫. It is used to find the general antiderivative of a function. A definite integral has limits and is represented by ∫a^b, where a and b are the lower and upper limits of integration. It is used to find the specific area under the curve of a function within a given interval.

4. How do you interpret the value of an integral?

The value of an integral represents the area under the curve of a function within a given interval. It can also represent the total change in a quantity over that interval. The sign of the value can indicate whether the area or change is positive or negative.

5. What are some real-world applications of finding integrals?

Finding integrals has many applications in physics, engineering, economics, and other fields. It can be used to calculate work, displacement, and velocity in physics problems. In economics, it can be used to calculate total revenue or total cost. In engineering, it can be used to find the center of mass and moment of inertia of an object.

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