Last updated on July 21st, 2025
We use the derivative of x-1, which is 1, as a tool to understand 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 x-1 in detail.
The derivative of x-1 is commonly represented as d/dx (x-1) or (x-1)', and its value is 1. The function x-1 has a clearly defined derivative, indicating it is differentiable within its domain.
The key concepts are mentioned below: Linear Function: Functions of the form ax + b.
Constant Rule: The derivative of any constant is zero.
Power Rule: For functions of the form x^n, the derivative is n*x^(n-1).
The derivative of x-1 can be denoted as d/dx (x-1) or (x-1)'.
The formula we use to differentiate x-1 is: d/dx (x-1) = 1
The formula applies to all x in the domain of real numbers.
We can derive the derivative of x-1 using proofs. To show this, we will use the rules of differentiation.
There are several methods we use to prove this, such as:
We will now demonstrate that the differentiation of x-1 results in 1 using the above-mentioned methods:
The derivative of x-1 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 using the first principle, we will consider f(x) = x-1.
Its derivative can be expressed as the following limit. f'(x) = limₕ→₀ [f(x + h) - f(x)] / h
Given that f(x) = x-1, we write f(x + h) = (x + h) - 1.
Substituting these into the equation, f'(x) = limₕ→₀ [(x + h - 1) - (x - 1)] / h = limₕ→₀ [x + h - 1 - x + 1] / h = limₕ→₀ h / h = limₕ→₀ 1 Hence, f'(x) = 1.
Using Power Rule
To prove the differentiation of x-1 using the power rule, We use the formula: d/dx (x^n) = n*x^(n-1) For f(x) = x, we have n = 1. d/dx (x) = 1*x^(1-1) = 1
Using Sum Rule We will now prove the derivative of x-1 using the sum rule.
The step-by-step process is demonstrated below: The sum rule states that the derivative of a sum is the sum of the derivatives.
Given f(x) = x - 1, we have two terms: x and -1.
The derivative of x is 1 (using the power rule), and the derivative of -1 is 0 (using the constant rule).
Thus, d/dx (x - 1) = 1 + 0 = 1
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.
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, 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).
For the function x-1, the derivative is always 1, regardless of the value of x. The function is continuous and differentiable at all points on the real number line.
Students frequently make mistakes when differentiating x-1. These mistakes can be resolved by understanding the proper solutions. Here are a few common mistakes and ways to solve them:
Calculate the derivative of (x-1)²
Here, we have f(x) = (x-1)². Using the chain rule, f'(x) = 2(x-1) * d/dx(x-1) d/dx(x-1) = 1, so f'(x) = 2(x-1) * 1 f'(x) = 2(x-1) Thus, the derivative of the specified function is 2(x-1).
We find the derivative of the given function by applying the chain rule. The first step is finding its derivative and then simplifying the expression to get the final result.
A car travels at a speed represented by the function y = x-1, where y represents the car's speed in km/h over time x in hours. If x = 3 hours, measure the speed of the car.
We have y = x-1 (speed of the car)...(1)
The derivative of y with respect to x is 1, indicating a constant rate of change. Given x = 3 hours, substitute this into the function: y = 3 - 1 = 2 km/h
Hence, the car's speed at 3 hours is 2 km/h.
We find the speed of the car by evaluating the function at x = 3.
Since the derivative is 1, it indicates the speed is constant over time.
Derive the second derivative of the function y = x-1.
The first step is to find the first derivative, dy/dx = 1... (1)
Now we will differentiate equation (1) to get the second derivative: d²y/dx² = d/dx [1]
Since the derivative of a constant is 0, d²y/dx² = 0
Therefore, the second derivative of the function y = x-1 is 0.
We use the step-by-step process, where we start with the first derivative. The second derivative of a constant is zero, simplifying the process.
Prove: d/dx ((x-1)²) = 2(x-1).
Let’s start using the chain rule: Consider y = (x-1)²
To differentiate, we use the chain rule: dy/dx = 2(x-1) * d/dx [x-1]
Since the derivative of x-1 is 1, dy/dx = 2(x-1) * 1
Substituting y = (x-1)², d/dx ((x-1)²) = 2(x-1)
Hence proved.
In this step-by-step process, we used the chain rule to differentiate the equation.
Then, we replace (x-1) with its derivative.
As a final step, we simplify the expression to derive the equation.
Solve: d/dx (x-1/x)
To differentiate the function, we use the quotient rule: d/dx (x-1/x) = (d/dx (x) * x - (x-1) * d/dx(x))/ x²
We will substitute d/dx (x) = 1 and d/dx (1) = 0 = (1 * x - (x-1) * 1) / x² = (x - x + 1) / x² = 1 / x²
Therefore, d/dx (x-1/x) = 1 / x²
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.
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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