Logarithmic function defined as an integral

In summary, the person is attempting to prove the rules for the logarithmic function using the integral definition. They are having trouble with the quotient rule and are seeking help. The suggestion is to use the Chain Rule to find all the properties of the log.
  • #1
JMR_2413
2
0
I'm attempting to prove the rules for the logarithmic function using the Integral definition: Log(x)=[1,x]∫1/t dt. I think I am alright with the product rule but I'm struggling with the quotient rule: i.e. Log(a/b)=Log(a)-Log(b). I believe that I'm having trouble breaking up the Integral correctly. Any help would be appreciated!
 
Physics news on Phys.org
  • #2
If you have already proved Log(a) + Log(b) = Log(ab) from the integral definition
and you want to prove Log(a/b) + Log(b) = Log(a),
just replace a by a/b everywhere in your proof.
 
  • #3
JMR_2413 said:
I'm attempting to prove the rules for the logarithmic function using the Integral definition: Log(x)=[1,x]∫1/t dt. I think I am alright with the product rule but I'm struggling with the quotient rule: i.e. Log(a/b)=Log(a)-Log(b). I believe that I'm having trouble breaking up the Integral correctly. Any help would be appreciated!

Try using the Chain Rule.

d/dxlog(a/x) = (x/a)(-a/x^2) = -1/x so log(a/x) = -log(x) + c.

Now calculate c.

The Chain Rule can be used to find all of the properties of the log once one sets log(1) to equal zero.
 

Related to Logarithmic function defined as an integral

1. What is a logarithmic function defined as an integral?

A logarithmic function defined as an integral is a mathematical function that is defined as the inverse of the exponential function. It is represented as logb(x) = ∫(1/x)dx, where b is the base of the logarithm and x is the input value.

2. How is a logarithmic function related to an exponential function?

A logarithmic function is the inverse of an exponential function. This means that if an exponential function is represented as y = bx, then the corresponding logarithmic function would be logb(y) = x.

3. What is the domain and range of a logarithmic function defined as an integral?

The domain of a logarithmic function defined as an integral is all positive real numbers. The range depends on the base of the logarithm, but it is always all real numbers.

4. How is the graph of a logarithmic function defined as an integral different from a regular logarithmic function?

The graph of a logarithmic function defined as an integral is a curve that approaches the x-axis asymptotically. This is because the integral of 1/x approaches infinity as x approaches 0. In contrast, the graph of a regular logarithmic function is a curve that approaches a vertical asymptote as x approaches 0.

5. In what real-world applications is a logarithmic function defined as an integral used?

A logarithmic function defined as an integral is used in many real-world applications, such as in finance, biology, and physics. It is commonly used to model exponential growth and decay, such as in population growth, radioactive decay, and compound interest calculations.

Similar threads

Replies
14
Views
825
Replies
14
Views
1K
Replies
3
Views
1K
Replies
2
Views
1K
Replies
11
Views
329
  • Calculus
Replies
4
Views
2K
Replies
2
Views
1K
Replies
1
Views
1K
Replies
2
Views
961
Replies
31
Views
1K
Back
Top