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Last updated on September 27, 2025

Derivative of ln(x/2)

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We use the derivative of ln(x/2), which is 1/x, as a measuring tool for how the logarithmic function changes in response to a slight change in x. Derivatives help us calculate profit or loss in real-life situations. We will now talk about the derivative of ln(x/2) in detail.

Derivative of ln(x/2) for US Students
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What is the Derivative of ln(x/2)?

We now understand the derivative of ln(x/2). It is commonly represented as d/dx (ln(x/2)) or (ln(x/2))', and its value is 1/x. The function ln(x/2) has a clearly defined derivative, indicating it is differentiable within its domain.

 

The key concepts are mentioned below:

 

Logarithmic Function: ln(x/2) = ln(x) - ln(2).

 

Quotient Rule: Rule for differentiating ln(x/2) (since it consists of ln(x) - ln(2)).

 

Natural Logarithm: ln(x) is the logarithm to the base e, a mathematical constant.

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Derivative of ln(x/2) Formula

The derivative of ln(x/2) can be denoted as d/dx (ln(x/2)) or (ln(x/2))'. The formula we use to differentiate ln(x/2) is: d/dx (ln(x/2)) = 1/x

 

The formula applies to all x where x > 0.

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Proofs of the Derivative of ln(x/2)

We can derive the derivative of ln(x/2) using proofs. To show this, we will use logarithmic identities along with the rules of differentiation.

 

There are several methods we use to prove this, such as: 

 

  • By First Principle 
     
  • Using Chain Rule 
     
  • Using Properties of Logarithms

 

We will now demonstrate that the differentiation of ln(x/2) results in 1/x using the above-mentioned methods:

 

By First Principle

 

The derivative of ln(x/2) can be proved using the First Principle, which expresses the derivative as the limit of the difference quotient. To find the derivative of ln(x/2) using the first principle, we will consider f(x) = ln(x/2). Its derivative can be expressed as the following limit. f'(x) = limₕ→₀ [f(x + h) - f(x)] / h Given that f(x) = ln(x/2), we write f(x + h) = ln((x + h)/2). Substituting these into the equation, f'(x) = limₕ→₀ [ln((x + h)/2) - ln(x/2)] / h = limₕ→₀ [ln((x + h)/x)] / h = limₕ→₀ ln(1 + h/x)/h = (1/x) limₕ→₀ ln(1 + h/x)/(h/x) Using limit formulas, limₕ→₀ ln(1 + u)/u = 1 as u → 0. f'(x) = 1/x Hence, proved.

 

Using Chain Rule

 

To prove the differentiation of ln(x/2) using the chain rule, We use the formula: ln(x/2) = ln(x) - ln(2). The derivative of a constant is zero, so d/dx(ln(2)) = 0. Thus, d/dx (ln(x/2)) = d/dx(ln(x)) = 1/x.

 

Using Properties of Logarithms

 

We use the property: ln(a/b) = ln(a) - ln(b). So, ln(x/2) = ln(x) - ln(2). Differentiating both sides, we have: d/dx (ln(x/2)) = d/dx(ln(x)) - d/dx(ln(2)) = 1/x - 0 = 1/x. Thus, the derivative of ln(x/2) is 1/x.

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Higher-Order Derivatives of ln(x/2)

When a function is differentiated several times, the derivatives obtained are referred to as higher-order derivatives. Higher-order derivatives can be a little tricky. To understand them better, think of a car where the speed changes (first derivative) and the rate at which the speed changes (second derivative) also changes. Higher-order derivatives make it easier to understand functions like ln(x/2).

 

For the first derivative of a function, we write f′(x), which indicates how the function changes or its slope at a certain point. The second derivative is derived from the first derivative, which is denoted using f′′(x). Similarly, the third derivative, f′′′(x), is the result of the second derivative, and this pattern continues.

 

For the nth Derivative of ln(x/2), we generally use f⁽ⁿ⁾(x) for the nth derivative of a function f(x), which tells us the change in the rate of change (continuing for higher-order derivatives).

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Special Cases:

When x approaches 0, the derivative is undefined because ln(x/2) is undefined for x ≤ 0.

 

When x is 2, the derivative of ln(x/2) = 1/2.

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Common Mistakes and How to Avoid Them in Derivatives of ln(x/2)

Students frequently make mistakes when differentiating ln(x/2).These mistakes can be resolved by understanding the proper solutions.

 

Here are a few common mistakes and ways to solve them:

Mistake 1

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Not simplifying the equation

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Students may forget to simplify the equation, which can lead to incomplete or incorrect results. They often skip steps and directly arrive at the result.

 

Ensure that each step is written in order. Students might think it is awkward, but it is important to avoid errors in the process.

Mistake 2

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Forgetting the Undefined Points of ln(x/2)

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They might not remember that ln(x/2) is undefined for x ≤ 0. Keep in mind that you should consider the domain of the function that you differentiate.

 

It will help you understand that the function is not continuous at certain points.

Mistake 3

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Incorrect use of Chain Rule

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While differentiating functions such as ln(x²/2), students misapply the chain rule. For example, incorrect differentiation: d/dx (ln(x²/2)) = 2x/x².

 

Instead, use the chain rule correctly: d/dx (ln(x²/2)) = (1/x²) * 2x = 2/x. To avoid this mistake, ensure the chain rule is applied properly.

Mistake 4

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Not writing Constants and Coefficients

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There is a common mistake where students forget to account for constants before ln(x/2). For example, they incorrectly write d/dx (3ln(x/2)) = 1/x.

 

Students should check the constants in the terms and ensure they are multiplied properly. For example, the correct equation is d/dx (3ln(x/2)) = 3/x.

Mistake 5

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Incorrectly Applying the Quotient Rule

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Students often incorrectly apply the quotient rule when differentiating logarithmic functions like ln(x/2). For example, incorrect: d/dx (ln(x/2)) = 2/x.

 

To fix this error, remember that ln(x/2) can be expanded as ln(x) - ln(2), and differentiate accordingly.

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Examples Using the Derivative of ln(x/2)

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Problem 1

Calculate the derivative of ln(x)·ln(x/2).

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Here, we have f(x) = ln(x)·ln(x/2). Using the product rule, f'(x) = u′v + uv′ In the given equation, u = ln(x) and v = ln(x/2). Let’s differentiate each term, u′ = d/dx (ln(x)) = 1/x v′ = d/dx (ln(x/2)) = 1/x Substituting into the given equation, f'(x) = (1/x)·ln(x/2) + ln(x)·(1/x) Let’s simplify terms to get the final answer, f'(x) = ln(x/2)/x + ln(x)/x Thus, the derivative of the specified function is [ln(x/2) + ln(x)]/x.

Explanation

We find the derivative of the given function by dividing the function into two parts.

The first step is finding its derivative and then combining them using the product rule to get the final result.

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Problem 2

A newly constructed building's height is represented by the function y = ln(x/2), where y represents the height at a distance x from the base. If x = 4 meters, measure the rate of height increase at that point.

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We have y = ln(x/2) (height of the building)...(1) Now, we will differentiate the equation (1). Take the derivative ln(x/2): dy/dx = 1/x Given x = 4 (substitute this into the derivative), dy/dx = 1/4 Hence, we get the rate of height increase at a distance x = 4 as 1/4.

Explanation

We find the rate of height increase at x = 4 as 1/4, which means that at a given point, the height of the building would rise at a rate that is a quarter of the horizontal distance.

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Problem 3

Derive the second derivative of the function y = ln(x/2).

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The first step is to find the first derivative, dy/dx = 1/x...(1) Now we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [1/x] = -1/x² Therefore, the second derivative of the function y = ln(x/2) is -1/x².

Explanation

We use the step-by-step process, where we start with the first derivative.

We then differentiate 1/x to find the second derivative and simplify the terms to get the final answer.

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Problem 4

Prove: d/dx (ln(x²/2)) = 2/x.

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Let’s start using the chain rule: Consider y = ln(x²/2) = ln(x²) - ln(2) To differentiate, we use the chain rule: dy/dx = d/dx (ln(x²)) - d/dx(ln(2)) = (1/x²) * 2x - 0 = 2/x Hence proved.

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation.

Then, we replace ln(x²) with its derivative. As a final step, we substitute the simplified form to derive the equation.

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Problem 5

Solve: d/dx (ln(x/2)/x).

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To differentiate the function, we use the quotient rule: d/dx (ln(x/2)/x) = (d/dx (ln(x/2)).x - ln(x/2).d/dx(x))/x² We will substitute d/dx (ln(x/2)) = 1/x and d/dx (x) = 1 = (1/x * x - ln(x/2) * 1)/x² = (1 - ln(x/2))/x² Therefore, d/dx (ln(x/2)/x) = (1 - ln(x/2))/x².

Explanation

In this process, we differentiate the given function using the quotient rule.

As a final step, we simplify the equation to obtain the final result.

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FAQs on the Derivative of ln(x/2)

1.Find the derivative of ln(x/2).

Using the properties of logarithms, ln(x/2) is equivalent to ln(x) - ln(2), and its derivative is 1/x.

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2.Can we use the derivative of ln(x/2) in real life?

Yes, we can use the derivative of ln(x/2) in real life in calculating the rate of change in various applications, especially in fields such as mathematics, physics, and economics.

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3.Is it possible to take the derivative of ln(x/2) at the point where x = 0?

No, x = 0 is a point where ln(x/2) is undefined, so it is impossible to take the derivative at these points (since the function does not exist there).

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4.What rule is used to differentiate ln(x/2)/x?

We use the quotient rule to differentiate ln(x/2)/x, resulting in (1 - ln(x/2))/x².

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5.Are the derivatives of ln(x/2) and ln(x) the same?

No, they are not the same. The derivative of ln(x/2) is 1/x due to the constant term ln(2), while the derivative of ln(x) is also 1/x, but without considering the constant.

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Important Glossaries for the Derivative of ln(x/2)

  • Derivative: The derivative of a function indicates how the given function changes in response to a slight change in x. Logarithmic

 

  • Function: A function involving a logarithm, such as ln(x/2).

 

  • Natural Logarithm: A logarithm to the base e, represented as ln(x).

 

  • Quotient Rule: A method for finding the derivative of a quotient of two functions.

 

  • Chain Rule: A technique for differentiating composite functions.
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Jaskaran Singh Saluja

About the Author

Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

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Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.

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