Chapter 4: Problem 51
Find \(f(x)\) if \(\int_{1}^{x} f(t) d t=2 x-2\)
Short Answer
Expert verified
The function \( f(x) = 2 \).
Step by step solution
01
Analyze the Given Integral Equation
We are given the equation \( \int_{1}^{x} f(t) \, dt = 2x - 2 \). The left-hand side of the equation represents the definite integral of the function \( f(t) \) from 1 to \( x \). The right-hand side simplifies to a linear expression in terms of \( x \).
02
Apply the Fundamental Theorem of Calculus
According to the Fundamental Theorem of Calculus, if \( F(x) \) is the antiderivative of \( f(t) \), then \( \frac{d}{dx} \int_{1}^{x} f(t) \, dt = f(x) \). This means \( f(x) = \frac{d}{dx} (2x - 2) \).
03
Differentiate the Right-Hand Side
Differentiate the expression \( 2x - 2 \) with respect to \( x \). The derivative is \( 2 \), since the derivative of \( 2x \) is 2 and the derivative of a constant \(-2\) is 0.
04
Conclude the Result
Since \( f(x) \) corresponds to the derivative of the expression \( 2x - 2 \), we have \( f(x) = 2 \). This means the function \( f(x) \) is a constant function equal to 2.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Definite Integral
The definite integral is a concept in calculus used to compute the accumulation of quantities. Simply put, it's a way of adding up a continuous range of values, such as areas under curves. In our problem, the definite integral is from 1 to \( x \), and it is written as:
- \( \int_{1}^{x} f(t) \, dt \)
Antiderivatives
Antiderivatives are closely related to the process of differentiation, but they work in reverse. If differentiating gives you the rate of change of a function (derivative), finding the antiderivative gives you the original function whose derivative was taken.
- If \( F(x) \) represents the antiderivative of \( f(t) \) over \( [1, x] \), then according to the Fundamental Theorem of Calculus: \( F(x) \) is such that \( F'(x) = f(x) \).
Differentiation
Differentiation is the process of calculating the derivative, which is the rate at which a function is changing at any given point. It's a core tool in calculus for understanding how functions behave.
- The derivative of \( 2x - 2 \) was calculated in the step-by-step solution to find \( f(x) \).
- The process involves applying the rule that the derivative of \( ax \) is \( a \), and the derivative of a constant is 0. Thus, for \( 2x - 2 \), the derivative is simply \( 2 \).