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Last updated on July 18th, 2025

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Derivative of 7lnx

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We use the derivative of 7ln(x), which is 7/x, as a measuring tool for how the natural logarithm 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 7ln(x) in detail.

Derivative of 7lnx for UK Students
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What is the Derivative of 7lnx?

We now understand the derivative of 7lnx. It is commonly represented as d/dx (7lnx) or (7lnx)', and its value is 7/x. The function 7lnx has a clearly defined derivative, indicating it is differentiable within its domain. The key concepts are mentioned below: Natural Logarithm Function: ln(x) is the natural logarithm of x. Constant Multiple Rule: Rule for differentiating 7lnx, where 7 is a constant. Reciprocal Rule: The derivative of ln(x) is 1/x.

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Derivative of 7lnx Formula

The derivative of 7lnx can be denoted as d/dx (7lnx) or (7lnx)'. The formula we use to differentiate 7lnx is: d/dx (7lnx) = 7/x (or) (7lnx)' = 7/x The formula applies to all x where x > 0.

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Proofs of the Derivative of 7lnx

We can derive the derivative of 7lnx using proofs. To show this, we will use the properties of logarithms along with the rules of differentiation. There are several methods we use to prove this, such as: Using the Constant Multiple Rule Using the Chain Rule Using the Product Rule We will now demonstrate that the differentiation of 7lnx results in 7/x using the above-mentioned methods: Using the Constant Multiple Rule The derivative of 7lnx can be proved using the constant multiple rule. The rule states that the derivative of a constant times a function is the constant times the derivative of the function. Consider f(x) = 7lnx. Its derivative can be expressed as: f'(x) = 7 * d/dx (lnx) Since d/dx (lnx) = 1/x, f'(x) = 7 * (1/x) = 7/x. Using the Chain Rule To prove the differentiation of 7lnx using the chain rule, We use the formula: lnx = ln(u), where u = x By chain rule: d/dx [ln(u)] = (1/u) * du/dx … (1) Let’s substitute u = x in equation (1), d/dx (7lnx) = 7 * (1/x) = 7/x Using the Product Rule We will now prove the derivative of 7lnx using the product rule. The step-by-step process is demonstrated below: Here, we use the formula, 7lnx = 7 * lnx Given that, u = 7 and v = lnx Using the product rule formula: d/dx [u.v] = u'v + uv' u' = d/dx (7) = 0 v' = d/dx (lnx) = 1/x d/dx (7lnx) = 0 * lnx + 7 * (1/x) d/dx (7lnx) = 7/x

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Higher-Order Derivatives of 7lnx

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 7lnx. 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 7lnx, we generally use fⁿ(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 from the positive side, the derivative approaches infinity because 7lnx has a vertical asymptote there. When x is 1, the derivative of 7lnx = 7/1, which is 7.

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Common Mistakes and How to Avoid Them in Derivatives of 7lnx

Students frequently make mistakes when differentiating 7lnx. 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, especially when solving using the product or chain rule. 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 Domain of lnx

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They might not remember that lnx 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 such certain points.

Mistake 3

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Incorrect use of Constant Multiple Rule

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While differentiating functions such as 7ln(x), students misapply the constant multiple rule. For example: Incorrect differentiation: d/dx (7ln(x)) = 1/x. Instead, apply the rule properly: d/dx (c * f(x)) = c * f'(x). To avoid this mistake, use the constant multiple rule correctly. Always check for errors in the calculation and ensure it is properly simplified.

Mistake 4

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Not writing Constants and Coefficients

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There is a common mistake that students at times forget to multiply the constants placed before lnx. For example, they incorrectly write d/dx (7lnx) = 1/x. Students should check the constants in the terms and ensure they are multiplied properly. For example, the correct equation is d/dx (7lnx) = 7/x.

Mistake 5

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Not Applying the Chain Rule

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Students often forget to use the chain rule. This happens when the derivative of the inner function is not considered. For example: Incorrect: d/dx (7ln(2x)) = 7/x. To fix this error, students should divide the functions into inner and outer parts. Then, make sure that each function is differentiated. For example, d/dx (7ln(2x)) = 7 * (1/2x) * 2 = 7/x.

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Examples Using the Derivative of 7lnx

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Problem 1

Calculate the derivative of (7lnx · x³)

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Here, we have f(x) = 7lnx · x³. Using the product rule, f'(x) = u′v + uv′ In the given equation, u = 7lnx and v = x³. Let’s differentiate each term, u′ = d/dx (7lnx) = 7/x v′ = d/dx (x³) = 3x² Substituting into the given equation, f'(x) = (7/x) · x³ + 7lnx · 3x² Let’s simplify terms to get the final answer, f'(x) = 7x² + 21lnx · x² Thus, the derivative of the specified function is 7x² + 21lnx · x².

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 company monitors the growth of its user database, which is represented by the function y = 7ln(x), where y represents the growth rate at time x. If x = 10 months, measure the growth rate.

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We have y = 7ln(x) (growth rate)...(1) Now, we will differentiate the equation (1) Take the derivative of 7ln(x): dy/dx = 7/x Given x = 10 (substitute this into the derivative) dy/dx = 7/10 Hence, we get the growth rate of the user database at x = 10 months as 0.7.

Explanation

We find the growth rate of the user database at x = 10 months as 0.7, which means that at 10 months, the growth is 0.7 units per month.

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Problem 3

Derive the second derivative of the function y = 7ln(x).

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The first step is to find the first derivative, dy/dx = 7/x...(1) Now we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [7/x] Here we use the quotient rule, d²y/dx² = -7/x² Therefore, the second derivative of the function y = 7ln(x) is -7/x².

Explanation

We use the step-by-step process, where we start with the first derivative. Using the quotient rule, we differentiate 7/x. We then substitute the identity and simplify the terms to find the final answer.

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Problem 4

Prove: d/dx (7ln(x²)) = 14/x.

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Let’s start using the chain rule: Consider y = 7ln(x²) y = 7 * ln(u), where u = x² To differentiate, we use the chain rule: dy/dx = 7 * (1/u) * du/dx Since du/dx = 2x, dy/dx = 7 * (1/x²) * 2x dy/dx = 14/x Hence proved.

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation. Then, we replace x² with its derivative. As a final step, we substitute y = 7ln(x²) to derive the equation.

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Problem 5

Solve: d/dx (7lnx/x)

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To differentiate the function, we use the quotient rule: d/dx (7lnx/x) = (d/dx (7lnx) · x - 7lnx · d/dx(x))/x² We will substitute d/dx (7lnx) = 7/x and d/dx (x) = 1 = (7/x · x - 7lnx · 1)/x² = (7 - 7lnx)/x² Therefore, d/dx (7lnx/x) = (7 - 7lnx)/x²

Explanation

In this process, we differentiate the given function using the product rule and quotient rule. As a final step, we simplify the equation to obtain the final result.

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FAQs on the Derivative of 7lnx

1.Find the derivative of 7lnx.

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2.Can we use the derivative of 7lnx in real life?

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3.Is it possible to take the derivative of 7lnx at the point where x = 0?

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4.What rule is used to differentiate 7lnx/x?

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5.Are the derivatives of 7lnx and ln(x) the same?

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6.Can we find the derivative of the 7lnx formula?

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Important Glossaries for the Derivative of 7lnx

Derivative: The derivative of a function indicates how the given function changes in response to a slight change in x. Natural Logarithm Function: ln(x) is the natural logarithm of x, indicating the power to which the number e must be raised to obtain x. Constant Multiple Rule: A rule stating that the derivative of a constant times a function is the constant times the derivative of the function. Second Derivative: The derivative of the first derivative, indicating the rate of change of the rate of change of a function. Asymptote: A line that a graph approaches but never touches or crosses, indicating where a function becomes undefined or unbounded.

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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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