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Last updated on July 18th, 2025

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Derivative of x^-1/2

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We use the derivative of x^-1/2, which is -1/2 * x^-3/2, as a tool to understand how the function changes in response to a slight change in x. Derivatives help us calculate various rates of change in real-life situations. We will now talk about the derivative of x^-1/2 in detail.

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What is the Derivative of x^-1/2?

We now understand the derivative of x^-1/2. It is commonly represented as d/dx (x^-1/2) or (x^-1/2)', and its value is -1/2 * x^-3/2. The function x^-1/2 has a clearly defined derivative, indicating it is differentiable within its domain. The key concepts are mentioned below: Power Function: (x^n where n = -1/2). Power Rule: Rule for differentiating x^n. Negative Exponent: A negative exponent indicates the reciprocal of the base raised to the absolute value of the exponent.

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Derivative of x^-1/2 Formula

The derivative of x^-1/2 can be denoted as d/dx (x^-1/2) or (x^-1/2)'. The formula we use to differentiate x^-1/2 is: d/dx (x^-1/2) = -1/2 * x^-3/2 The formula applies to all x where x > 0.

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Proofs of the Derivative of x^-1/2

We can derive the derivative of x^-1/2 using proofs. To show this, we will use the power rule of differentiation. There are several methods we use to prove this, such as: By First Principle Using Power Rule We will now demonstrate that the differentiation of x^-1/2 results in -1/2 * x^-3/2 using these methods: By First Principle The derivative of x^-1/2 can be proved using the First Principle, which expresses the derivative as the limit of the difference quotient. To find the derivative of x^-1/2 using the first principle, we will consider f(x) = x^-1/2. Its derivative can be expressed as the following limit. f'(x) = limₕ→₀ [f(x + h) - f(x)] / h … (1) Given that f(x) = x^-1/2, we write f(x + h) = (x + h)^-1/2. Substituting these into equation (1), f'(x) = limₕ→₀ [(x + h)^-1/2 - x^-1/2] / h Using algebraic manipulation to combine the fractions, = limₕ→₀ [(x^-1/2(1 - (x + h)^1/2/x^1/2))] / h As h approaches zero, we get the derivative, f'(x) = -1/2 * x^-3/2. Hence, proved. Using Power Rule To prove the differentiation of x^-1/2 using the power rule, We use the formula: d/dx (x^n) = n * x^(n-1). Substituting n = -1/2 in the power rule, d/dx (x^-1/2) = (-1/2) * x^(-1/2 - 1) = -1/2 * x^-3/2. Thus, the derivative of x^-1/2 is -1/2 * x^-3/2.

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Higher-Order Derivatives of x^-1/2

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 x^-1/2. 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 x^-1/2, 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 is 0, the derivative is undefined because x^-1/2 has a vertical asymptote there. When x is 1, the derivative of x^-1/2 = -1/2 * 1^-3/2, which is -1/2.

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Common Mistakes and How to Avoid Them in Derivatives of x^-1/2

Students frequently make mistakes when differentiating x^-1/2. 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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Incorrect application of the power rule

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Students may incorrectly apply the power rule by not adjusting the exponent properly. For example, they might incorrectly write the derivative as -1/2 * x^-1/2 instead of -1/2 * x^-3/2. Ensure that each step follows the power rule correctly by subtracting 1 from the exponent.

Mistake 2

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Forgetting the undefined point at x = 0

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Students might not remember that the function x^-1/2 is undefined at x = 0. Keep in mind that you should consider the domain of the function you differentiate. It will help you understand that the function is not continuous at certain points.

Mistake 3

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Not simplifying expressions

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While differentiating, students may forget to simplify the result, especially when dealing with negative exponents. For example, failing to express the final answer in a simplified form with positive exponents. Always simplify your final expression for clarity.

Mistake 4

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Confusing the roles of constants and coefficients

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There is a common mistake where students forget to multiply the constants properly when differentiating. For example, if the function is 5x^-1/2, they might forget the 5 and write the derivative as -1/2 * x^-3/2 instead of -5/2 * x^-3/2. Always check for constants and ensure they are multiplied correctly.

Mistake 5

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Not applying the chain rule when necessary

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Students often forget to use the chain rule when dealing with composite functions. For example, for d/dx ((2x)^-1/2), they might incorrectly write -1/2 * (2x)^-3/2 instead of taking into account the inner derivative. Make sure to identify inner functions and apply the chain rule appropriately.

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Examples Using the Derivative of x^-1/2

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Problem 1

Calculate the derivative of (x^-1/2 * x^3).

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Here, we have f(x) = x^-1/2 * x^3. Using the product rule, f'(x) = u′v + uv′ In the given equation, u = x^-1/2 and v = x^3. Let’s differentiate each term, u′ = d/dx (x^-1/2) = -1/2 * x^-3/2 v′ = d/dx (x^3) = 3x^2 Substituting into the given equation, f'(x) = (-1/2 * x^-3/2) * x^3 + (x^-1/2) * 3x^2 Let’s simplify terms to get the final answer, f'(x) = -1/2 * x^3/2 + 3x^3/2 Thus, the derivative of the specified function is (5/2) * x^3/2.

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 chemical concentration decreases over time according to the function C(t) = t^-1/2. Calculate the rate of change of concentration at t = 4 hours.

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We have C(t) = t^-1/2 (concentration function)...(1) Now, we will differentiate the equation (1) Take the derivative of t^-1/2: dC/dt = -1/2 * t^-3/2 Given t = 4 (substitute this into the derivative) dC/dt = -1/2 * (4)^-3/2 = -1/2 * 1/8 = -1/16 Hence, the rate of change of concentration at t = 4 hours is -1/16.

Explanation

We find the rate of change of concentration at t = 4 hours as -1/16, which means the concentration is decreasing at that rate at that specific time.

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Problem 3

Derive the second derivative of the function y = x^-1/2.

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The first step is to find the first derivative, dy/dx = -1/2 * x^-3/2...(1) Now we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [-1/2 * x^-3/2] = -1/2 * (-3/2 * x^-5/2) = 3/4 * x^-5/2 Therefore, the second derivative of the function y = x^-1/2 is 3/4 * x^-5/2.

Explanation

We use the step-by-step process, where we start with the first derivative. Using the power rule, we differentiate -1/2 * x^-3/2. We then simplify the terms to find the final answer.

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Problem 4

Prove: d/dx ((3x)^-1/2) = -3/2 * (3x)^-3/2.

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Let’s start using the chain rule: Consider y = (3x)^-1/2 To differentiate, we use the chain rule: dy/dx = -1/2 * (3x)^-3/2 * d/dx(3x) Since the derivative of 3x is 3, dy/dx = -1/2 * (3x)^-3/2 * 3 = -3/2 * (3x)^-3/2 Hence proved.

Explanation

In this step-by-step process, we used the chain rule to differentiate the equation. Then, we replace 3x with its derivative. As a final step, we substitute y = (3x)^-1/2 to derive the equation.

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Problem 5

Solve: d/dx ((x^2)/x^-1/2).

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To differentiate the function, we use the quotient rule: d/dx ((x^2)/x^-1/2) = (d/dx (x^2) * x^-1/2 - x^2 * d/dx (x^-1/2)) / (x^-1/2)^2 We will substitute d/dx (x^2) = 2x and d/dx (x^-1/2) = -1/2 * x^-3/2 = (2x * x^-1/2 - x^2 * (-1/2 * x^-3/2)) / (x^-1) = (2x^1/2 + 1/2 * x^3/2) / (x^-1) Therefore, d/dx ((x^2)/x^-1/2) = (5/2) * x^1/2.

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 x^-1/2

1.Find the derivative of x^-1/2.

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2.Can we use the derivative of x^-1/2 in real life?

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3.Is it possible to take the derivative of x^-1/2 at the point where x = 0?

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4.What rule is used to differentiate x^-1/2 * x?

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5.Are the derivatives of x^-1/2 and (x^-1/2)^-1 the same?

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Important Glossaries for the Derivative of x^-1/2

Derivative: The derivative of a function indicates how the given function changes in response to a slight change in x. Power Rule: A differentiation rule used for functions of the form x^n. Negative Exponent: An exponent that indicates the reciprocal of the base raised to the absolute value of the exponent. Reciprocal: A value that, when multiplied by the original number, results in 1. Asymptote: A line that a curve approaches without crossing.

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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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