Is $\frac{\ln{|x|}}{x}=\ln{|x^{-x}|}$? Explained by y $\ln{x}=\ln{x^y}$ Rule

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In summary, the conversation discusses the rule y ln(x) = ln(x^y) and its application to the equation \frac{\ln{|x|}}{x}=\ln{|x^{-x}|}. It is mentioned that the exponent can be brought inside the absolute value, but not in all cases.
  • #1
find_the_fun
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Is \(\displaystyle \frac{\ln{|x|}}{x}=\ln{|x^{-x}|}\) because of the rule \(\displaystyle y \ln{x}=\ln{x^y}\)?
 
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  • #2
Yep! And in general, you can bring the exponent inside the absolute value.
 
  • #3
Rido12 said:
Yep! And in general, you can bring the exponent inside the absolute value.

Oh cool, usually my answer key makes these sorts of simplifications but it didn't for this one.
 
  • #4
find_the_fun said:
Is \(\displaystyle \frac{\ln{|x|}}{x}=\ln{|x^{-x}|}\) because of the rule \(\displaystyle y \ln{x}=\ln{x^y}\)?

Applying that rule gives us:
$$\frac{\ln{|x|}}{x}=\ln{\left(|x|^{1/x}\right)}$$
And I'm afraid we can't generally bring that power inside the absolute signs.
 
  • #5


No, the two expressions are not equivalent. The first expression, $\frac{\ln{|x|}}{x}$, is a logarithmic function with a variable base of $e$ and a variable exponent of $x$. The second expression, $\ln{|x^{-x}|}$, is a logarithmic function with a base of $e$ and an exponent of $-x$. The two expressions have different bases and exponents, therefore they are not equal.

The rule $y\ln{x}=\ln{x^y}$ only applies when both the base and exponent are constants. In this case, $x$ is a variable, so the rule cannot be used to equate the two expressions. It is important to carefully consider the properties of logarithmic functions and their rules before attempting to equate expressions involving them.
 

FAQ: Is $\frac{\ln{|x|}}{x}=\ln{|x^{-x}|}$? Explained by y $\ln{x}=\ln{x^y}$ Rule

What is the rule $\ln{x}=\ln{x^y}$ used for?

The rule $\ln{x}=\ln{x^y}$ is used to simplify logarithmic expressions where the base and the argument are the same. It states that the natural logarithm of a number raised to a power is equal to the product of the power and the natural logarithm of the number. This rule is also known as the power property of logarithms.

Is $\frac{\ln{|x|}}{x}$ equivalent to $\ln{|x^{-x}|}$?

Yes, $\frac{\ln{|x|}}{x}$ is equivalent to $\ln{|x^{-x}|}$ when the base and the argument of the logarithm are the same. This is because the rule $\ln{x}=\ln{x^y}$ can be applied to simplify the expression to $\ln{|x^{1-x}|}$. Then, using the power property again, we get $\ln{|x^{-x}|}$.

Can the rule $\ln{x}=\ln{x^y}$ be used for any base?

No, the rule $\ln{x}=\ln{x^y}$ only applies to natural logarithms, where the base is the irrational number $e$. For logarithms with other bases, different rules or properties may be used to simplify expressions.

Are there any restrictions on the values of $x$ for the rule $\ln{x}=\ln{x^y}$ to be valid?

Yes, the rule $\ln{x}=\ln{x^y}$ is only valid when $x$ is a positive number. This is because the natural logarithm function is only defined for positive inputs. When $x$ is negative, the expression $\ln{|x|}$ is undefined.

How can the rule $\ln{x}=\ln{x^y}$ be helpful in solving logarithmic equations?

The rule $\ln{x}=\ln{x^y}$ can be used to simplify logarithmic equations by reducing them to a form where the argument and the base are the same. This makes it easier to solve the equation using algebraic methods. It can also be used to convert exponential equations into logarithmic form, which can be helpful in solving certain types of equations.

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