Can Someone Explain This Logarithmic Property Discrepancy?

In summary: Let's start with the definition of log_c. What is it? How can you prove that log_c\left(a^b\right)= b log_c(a) using the definition of log_c? In summary, the conversation is about a question regarding logarithmic properties and the equation (log base c of a)^b = b (log base c of a). The person is having trouble understanding the equation and is asking for an explanation. However, the equation is incorrect and the correct expression is (log base c of a^b) = b (log base c of a). The person is then asked to prove this using the definition of log_c.
  • #1
Rafe
2
0
sorry this should go under the " Homework, Coursework, & Textbook Questions" forum. please delete. i will repost.

Okay i did a search for logarithmic properties and logarithms and couldn't seem to find an explanation for how this particular property works.
(log base c of a ) ^ b = b (log base c of a)
when i input simple numbers like :
PHP:
a=4
b=3
c=2
Log base 2 of 4 obvioussly the answer is 2, but
2^3 /= (does not equel) 3 x 2.
i dont' know how to make sense of this discrepency. i imagine I'm just reading it wrong.
 
Last edited:
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  • #2
You must be reading it wrong. Let x=(log base c of a). Then your equation reads x^b=bx, which in general is wrong.

A correct expression is:

(log base c of a^b)=b(log base c of a)

It looks close to what you wrote, so it may be what was meant.
 
  • #3
Rafe said:
sorry this should go under the " Homework, Coursework, & Textbook Questions" forum. please delete. i will repost.

Okay i did a search for logarithmic properties and logarithms and couldn't seem to find an explanation for how this particular property works.
(log base c of a ) ^ b = b (log base c of a)
when i input simple numbers like :
PHP:
a=4
b=3
c=2
Log base 2 of 4 obvioussly the answer is 2, but
2^3 /= (does not equel) 3 x 2.
i dont' know how to make sense of this discrepency. i imagine I'm just reading it wrong.

As mathman said, what you have: (log base c of a)^b = b(log base c of a), more simply written as
[tex]\left(log_c a\right)^b= b log_c a[/tex]
is not true.

Yes, you are reading it wrong. What is true is that
[tex]log_c\left(a^b\right)= b log_c(a)[/tex]

How you would prove that depends on exactly which definition of [itex]log_c[/itex] you are using.
 

1. What is a logarithm?

A logarithm is a mathematical function that represents the power to which a base number must be raised to produce a given number. In other words, it is the inverse of exponentiation.

2. What are the properties of logarithms?

The five main properties of logarithms are: product property, quotient property, power property, change of base property, and logarithm of 1 property. These properties allow for simplification of complex logarithmic expressions.

3. How do you simplify logarithmic expressions?

To simplify logarithmic expressions, you can use the properties of logarithms to combine or rewrite the terms in a more condensed form. You can also use the rules of exponents to simplify the expression further.

4. What is the difference between natural logarithms and common logarithms?

Natural logarithms, represented by the symbol ln, use the base e (approximately equal to 2.718) while common logarithms, represented by the symbol log, use the base 10. Natural logarithms are often used in calculus and other mathematical applications, while common logarithms are used more frequently in real-world situations.

5. How are logarithmic properties used in real life?

Logarithmic properties are used in various fields such as finance, engineering, and science to solve problems involving exponential growth or decay. They are also used in data analysis and modeling, such as in the Richter scale for measuring earthquake intensity.

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