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Last updated on July 15th, 2025

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Derivative of 2tanx

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We use the derivative of 2tan(x), which is 2sec²(x), as a measuring tool for how the 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 2tan(x) in detail.

Derivative of 2tanx for UK Students
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What is the Derivative of 2tanx?

We now understand the derivative of 2tanx. It is commonly represented as d/dx (2tanx) or (2tanx)', and its value is 2sec²x. The function 2tanx has a clearly defined derivative, indicating it is differentiable within its domain. The key concepts are mentioned below: Tangent Function: (tan(x) = sin(x)/cos(x)). Quotient Rule: Rule for differentiating tan(x) (since it consists of sin(x)/cos(x)). Secant Function: sec(x) = 1/cos(x).

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Derivative of 2tanx Formula

The derivative of 2tanx can be denoted as d/dx (2tanx) or (2tanx)'. The formula we use to differentiate 2tanx is: d/dx (2tanx) = 2sec²x (or) (2tanx)' = 2sec²x The formula applies to all x where cos(x) ≠ 0.

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Proofs of the Derivative of 2tanx

We can derive the derivative of 2tanx using proofs. To show this, we will use the trigonometric 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 Product Rule We will now demonstrate that the differentiation of 2tanx results in 2sec²x using the above-mentioned methods: *By First Principle* The derivative of 2tanx can be proved using the First Principle, which expresses the derivative as the limit of the difference quotient. To find the derivative of 2tanx using the first principle, we will consider f(x) = 2tanx. Its derivative can be expressed as the following limit. f'(x) = limₕ→₀ [f(x + h) - f(x)] / h … (1) Given that f(x) = 2tanx, we write f(x + h) = 2tan(x + h). Substituting these into equation (1), f'(x) = limₕ→₀ [2tan(x + h) - 2tanx] / h = limₕ→₀ 2[tan(x + h) - tanx] / h = 2limₕ→₀ [ [sin(x + h)/cos(x + h)] - [sinx/cosx] ] / h = 2limₕ→₀ [ [sin(x + h)cosx - cos(x + h)sinx] / [cosx·cos(x + h)] ]/ h We now use the formula sinA cosB - cosA sinB = sin(A - B). f'(x) = 2limₕ→₀ [ sinh / [ h cosx·cos(x + h)] ] = 2limₕ→₀ (sinh)/h · limₕ→₀ 1 / [cosx·cos(x + h)] Using limit formulas, limₕ→₀ (sinh)/h = 1. f'(x) = 2 [ 1 / (cosx·cos(x + 0))] = 2/cos²x As the reciprocal of cosine is secant, we have, f'(x) = 2sec²x. Hence, proved. *Using Chain Rule* To prove the differentiation of 2tanx using the chain rule, We use the formula: 2tanx = 2(sinx/cosx) Consider f(x) = sinx and g(x)= cosx So we get, tanx = f(x)/g(x) By quotient rule: d/dx [f(x) / g(x)] = [f'(x)g(x) - f(x)g'(x)] / [g(x)]² … (1) Let’s substitute f(x) = sinx and g(x) = cosx in equation (1), d/dx (tanx) = [(cosx)(cosx)- (sinx)(-sinx)]/ (cosx)² (cos²x+sin²x)/cos²x …(2) Here, we use the formula: (cos²x) + (sin²x) = 1 (Pythagorean identity) Substituting this into (2), d/dx (tanx) = 1/(cosx)² Since secx = 1/cosx, we write: d/dx(tanx) = sec²x Therefore, d/dx(2tanx) = 2sec²x. *Using Product Rule* We will now prove the derivative of 2tanx using the product rule. The step-by-step process is demonstrated below: Here, we use the formula, 2tanx = 2(sinx/cosx) 2tanx = 2(sinx)·(cosx)⁻¹ Given that, u = 2sinx and v = (cosx)⁻¹ Using the product rule formula: d/dx [u·v] = u'·v + u·v' u' = d/dx (2sinx) = 2cosx. (substitute u = 2sinx) Here we use the chain rule: v = (cosx)⁻¹ = (cosx)⁻¹ (substitute v = (cosx)⁻¹) v' = -1·(cosx)⁻²·d/dx (cosx) v' = sinx/(cosx)² Again, use the product rule formula: d/dx (2tanx) = u'·v + u·v' Let’s substitute u = 2sinx, u' = 2cosx, v = (cosx)⁻¹, and v' = sinx/(cosx)² When we simplify each term: We get, d/dx (2tanx) = 2[1 + sin²x/(cosx)²] sin²x/(cosx)² = tan²x (we use the identity sin²x + cos²x = 1) Thus: d/dx (2tanx) = 2[1 + tan²x] Since, 1 + tan²x = sec²x d/dx (2tanx) = 2sec²x.

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Higher-Order Derivatives of 2tanx

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 2tan(x). 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 2tan(x), 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 is π/2, the derivative is undefined because tan(x) has a vertical asymptote there. When x is 0, the derivative of 2tanx = 2sec²(0), which is 2.

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Common Mistakes and How to Avoid Them in Derivatives of 2tanx

Students frequently make mistakes when differentiating 2tanx. 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 Undefined Points of Tanx

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They might not remember that tanx is undefined at the points such as (x = π/2, 3π/2,...). 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 Quotient Rule

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While differentiating functions such as 2tanx/x, students misapply the quotient rule. For example: Incorrect differentiation: d/dx (2tanx/x) = 2sec²x/x². d/dx (u/v) = (v·u' - u·v')/v² (where u = 2tanx and v = x) Applying the quotient rule, d/dx (2tanx/x) = (x·2sec²x - 2tanx)/x² To avoid this mistake, write the quotient rule without errors. 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 tanx. For example, they incorrectly write d/dx (5tanx) sec²x. Students should check the constants in the terms and ensure they are multiplied properly. For e.g., the correct equation is d/dx (5tanx) = 5sec²x.

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 (tan(2x)) sec²(2x). 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 (tan(2x)) 2sec²(2x).

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Examples Using the Derivative of 2tanx

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Problem 1

Calculate the derivative of (2tanx·sec²x)

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Here, we have f(x) = 2tanx·sec²x. Using the product rule, f'(x) = u′v + uv′ In the given equation, u = 2tanx and v = sec²x. Let’s differentiate each term, u′= d/dx (2tanx) = 2sec²x v′= d/dx (sec²x) = 2sec²x tanx substituting into the given equation, f'(x) = (2sec²x)·(sec²x) + (2tanx)·(2sec²x tanx) Let’s simplify terms to get the final answer, f'(x) = 2sec⁴x + 4sec²x tan²x Thus, the derivative of the specified function is 2sec⁴x + 4sec²x tan²x.

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 water tank is being filled and its height is modeled by the function h(x) = 2tan(x) where h represents the height of water in meters as a function of time x in hours. If x = π/6, find the rate at which the height is increasing.

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We have h(x) = 2tan(x) (rate of height increase)...(1) Now, we will differentiate the equation (1) Take the derivative 2tan(x): dh/dx = 2sec²(x) Given x = π/6 (substitute this into the derivative) 2sec²(π/6) = 2[1 + tan²(π/6)] 2sec²(π/6) = 2[1 + (1/√3)²] = 2[1 + 1/3] = 2×4/3 = 8/3 Hence, the rate at which the height is increasing when x = π/6 is 8/3 meters per hour.

Explanation

We find the rate of height increase at x = π/6 by first differentiating the function and then substituting the value of x into the derivative to calculate the rate.

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Problem 3

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

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The first step is to find the first derivative, dy/dx = 2sec²(x)...(1) Now we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [2sec²(x)] Here we use the product rule, d²y/dx² = 2[sec²(x)·tan(x)] 2sec²(x) tan(x) Therefore, the second derivative of the function y = 2tan(x) is 4sec²(x) tan(x).

Explanation

We use the step-by-step process, where we start with the first derivative. Using the product rule, we differentiate sec²(x). We then substitute the identity and simplify the terms to find the final answer.

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Problem 4

Prove: d/dx (2tan²(x)) = 4tan(x) sec²(x).

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Let’s start using the chain rule: Consider y = 2tan²(x) [2tan(x)]² To differentiate, we use the chain rule: dy/dx = 4tan(x)·d/dx [tan(x)] Since the derivative of tan(x) is sec²(x), dy/dx = 4tan(x)·sec²(x) Substituting y = 2tan²(x), d/dx (2tan²(x)) = 4tan(x)·sec²(x) Hence proved.

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation. Then, we replace tan(x) with its derivative. As a final step, we substitute y = 2tan²(x) to derive the equation.

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Problem 5

Solve: d/dx (2tanx/x)

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To differentiate the function, we use the quotient rule: d/dx (2tanx/x) = (d/dx (2tanx)·x - 2tanx·d/dx(x))/x² We will substitute d/dx (2tanx) = 2sec²x and d/dx (x) = 1 (2sec²x·x - 2tanx)/x² = (2x sec²x - 2tanx)/x² Therefore, d/dx (2tanx/x) = (2x sec²x - 2tanx)/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 2tanx

1.Find the derivative of 2tanx.

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

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3.Is it possible to take the derivative of 2tanx at the point where x = π/2?

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4.What rule is used to differentiate 2tanx/x?

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5.Are the derivatives of 2tanx and 2tan⁻¹x the same?

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6.Can we find the derivative of the 2tanx formula?

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Important Glossaries for the Derivative of 2tanx

Derivative: The derivative of a function indicates how the given function changes in response to a slight change in x. Tangent Function: The tangent function is one of the primary six trigonometric functions and is written as tanx. Secant Function: A trigonometric function that is the reciprocal of the cosine function. It is typically represented as secx. First Derivative: It is the initial result of a function, which gives us the rate of change of a specific function. Quotient Rule: A rule used to differentiate functions that are the division of two other 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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