Chapter 5: Problem 11
Let \(f(t)=F^{\prime}(t) .\) Write the integral \(\int_{a}^{b} f(t) d t\) and evaluate it using the Fundamental Theorem of Calculus. $$F(t)=\ln t ; a=1, b=5$$
Short Answer
Expert verified
The integral evaluates to \( \ln 5 \).
Step by step solution
01
Identify the Relationship
Given that \( f(t) = F'(t) \) and \( F(t) = \ln t \), we begin by finding \( f(t) \) since it is the derivative of \( F(t) \).
02
Differentiate the Function
To find \( f(t) \), differentiate \( F(t) = \ln t \) with respect to \( t \). This gives:\[ f(t) = F'(t) = \frac{d}{dt}(\ln t) = \frac{1}{t}. \]
03
Write the Integral
We need to evaluate the integral \( \int_{a}^{b} f(t) \, dt \). With \( f(t) = \frac{1}{t} \), this becomes:\[ \int_{1}^{5} \frac{1}{t} \, dt. \]
04
Apply the Fundamental Theorem of Calculus
The Fundamental Theorem of Calculus states that if \( f \) is continuous on \([a, b]\) and \( F \) is an antiderivative of \( f \) on \([a, b]\), then:\[ \int_{a}^{b} f(t) \, dt = F(b) - F(a). \]Since \( F(t) = \ln t \), we use this to find: \[ \int_{1}^{5} \frac{1}{t} \, dt = F(5) - F(1) = \ln 5 - \ln 1. \]
05
Simplify the Result
We know from the properties of logarithms that \( \ln 1 = 0 \). Therefore, the expression simplifies to:\[ \ln 5 - 0 = \ln 5. \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Differentiation
Differentiation is a fundamental concept in calculus that involves the computation of a derivative. A derivative represents the rate at which a function changes at any given point. In simpler terms, it tells us the "slope" of the function at a specific location.
For the given function, where we have \( F(t) = \ln t \), differentiation helps us find the function \( f(t) \), which is the derivative of \( F(t) \). This process involves applying standard differentiation rules. The derivative of a logarithmic function \( \ln t \) is \( \frac{1}{t} \).
For the given function, where we have \( F(t) = \ln t \), differentiation helps us find the function \( f(t) \), which is the derivative of \( F(t) \). This process involves applying standard differentiation rules. The derivative of a logarithmic function \( \ln t \) is \( \frac{1}{t} \).
- Finding a derivative often involves rules like the power rule, chain rule, product rule, and quotient rule.
- In this exercise, we made use of the derivative of the natural logarithm.
Antiderivative
An antiderivative is essentially the reverse of differentiation. It is often referred to as integration, which is a core part of calculating areas under curves.
An antiderivative of a function \( f(t) \) is another function \( F(t) \) such that \( F'(t) = f(t) \). This means that if we differentiate \( F(t) \), we get back \( f(t) \).
In the given exercise, the function \( F(t) = \ln t \) is actually the antiderivative of \( f(t) = \frac{1}{t} \). When applying the Fundamental Theorem of Calculus, we need the antiderivative to evaluate the definite integral \( \int_{a}^{b} f(t) \, dt \).
An antiderivative of a function \( f(t) \) is another function \( F(t) \) such that \( F'(t) = f(t) \). This means that if we differentiate \( F(t) \), we get back \( f(t) \).
In the given exercise, the function \( F(t) = \ln t \) is actually the antiderivative of \( f(t) = \frac{1}{t} \). When applying the Fundamental Theorem of Calculus, we need the antiderivative to evaluate the definite integral \( \int_{a}^{b} f(t) \, dt \).
- The Fundamental Theorem of Calculus links differentiation and integration, stating that if you have an antiderivative, you can calculate the definite integral of a function.
- It assures us that given \( f(t) \) continuous on an interval, then \( \int_{a}^{b} f(t) \, dt = F(b) - F(a) \).
Logarithmic Function
The logarithmic function \( \ln t \) represents the natural logarithm. Logarithms are mathematical functions that are the inverses of exponentiation. The base of the natural logarithm is \( e \), an irrational constant approximately equal to \( 2.718 \).
Logarithms answer the question, "To what exponent must the base \( e \) be raised to produce this number?" For instance, \( \ln 5 \) tells us the power to which \( e \) must be raised to equal 5.
Logarithms answer the question, "To what exponent must the base \( e \) be raised to produce this number?" For instance, \( \ln 5 \) tells us the power to which \( e \) must be raised to equal 5.
- Logarithmic functions efficiently model growth and decay processes, making them useful in various scientific applications.
- \( \ln 1 = 0 \) because \( e^0 = 1 \), which simplifies calculations during integration as seen in our step-by-step solution.