Chapter 5: Problem 188
In the following exercises, evaluate each definite integral using the Fundamental Theorem of Calculus, Part 2 . $$ \int_{1}^{2}\left(\frac{1}{t^{2}}-\frac{1}{t^{3}}\right) d t $$
Short Answer
Expert verified
The integral evaluates to \( \frac{1}{8} \).
Step by step solution
01
Identify the Integrand
The given definite integral is \( \int_{1}^{2} \left( \frac{1}{t^{2}} - \frac{1}{t^{3}} \right) dt \). We need to evaluate this integral by finding its antiderivative.
02
Find the Antiderivative
The antiderivative of \( \frac{1}{t^2} \) is \( -\frac{1}{t} \), and the antiderivative of \( \frac{1}{t^3} \) is \( -\frac{1}{2t^2} \). Thus, the antiderivative of the integrand \( \frac{1}{t^2} - \frac{1}{t^3} \) is: \[ F(t) = -\frac{1}{t} + \frac{1}{2t^2} \]
03
Apply the Fundamental Theorem of Calculus
According to the Fundamental Theorem of Calculus, Part 2, the definite integral from 1 to 2 of a function is the difference between the values of its antiderivative at these points. Therefore, evaluate: \[ \int_{1}^{2} \left( \frac{1}{t^2} - \frac{1}{t^3} \right) dt = F(2) - F(1) \]
04
Evaluate F(2) and F(1)
Calculate \( F(2) \): \( -\frac{1}{2} + \frac{1}{8} = -\frac{4}{8} + \frac{1}{8} = -\frac{3}{8} \). Calculate \( F(1) \): \( -1 + \frac{1}{2} = -\frac{2}{2} + \frac{1}{2} = -\frac{1}{2} \).
05
Calculate the Definite Integral
Substitute \( F(2) \) and \( F(1) \) into the expression \( F(2) - F(1) \), which gives: \[ -\frac{3}{8} - \left(-\frac{1}{2}\right) = -\frac{3}{8} + \frac{4}{8} = \frac{1}{8} \]
06
Conclusion: Evaluate the Integral
The value of the definite integral \( \int_{1}^{2} \left( \frac{1}{t^2} - \frac{1}{t^3} \right) dt \) is \( \frac{1}{8} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Definite Integral
The idea of a definite integral is central in calculus. It represents the accumulation of quantities, such as area under a curve, between two specified limits, often written as \( a \) and \( b \). This is in contrast to an indefinite integral, which does not have specified limits. The notation for a definite integral is \( \int_{a}^{b} f(x) \, dx \), where \( f(x) \) is the function (or integrand) we are integrating.
- The definite integral calculates the net difference between the integrand's antiderivative evaluated at \( b \) and \( a \).
- In our example, the integral from 1 to 2 is represented as \( \int_{1}^{2} \left( \frac{1}{t^{2}} - \frac{1}{t^{3}} \right) dt \).
- This requires finding the antiderivative of the function within the given limits, revealing the accumulation of the function from \( t = 1 \) to \( t = 2 \).
Antiderivative
The antiderivative, also known as the indefinite integral, is a function that "undoes" the operation of differentiation. It is the function \( F(x) \) whose derivative \( F'(x) \) equals the given function \( f(x) \).
- To find an antiderivative, we essentially reverse the derivative process for each part of the integrand.
- For example, given the terms \( \frac{1}{t^2} \) and \( \frac{1}{t^3} \), we find they correspond to \( -\frac{1}{t} \) and \( -\frac{1}{2t^2} \), respectively, as their antiderivatives.
- Thus, the antiderivative of \( \frac{1}{t^2} - \frac{1}{t^3} \) is \( F(t) = -\frac{1}{t} + \frac{1}{2t^2} \).
Evaluation of Integrals
Evaluating an integral, especially a definite one, involves several clear steps. This process is essential for finding the exact value that a function accumulates over an interval.
- First, determine the antiderivative of the integrand. This represents the accumulation function for the original rate of change expressed by the integrand.
- Next, apply the Fundamental Theorem of Calculus. This theorem states that to compute \( \int_{a}^{b} f(x) \, dx \), you subtract the antiderivative of \( f(x) \) evaluated at \( a \) from its value at \( b \).
- For our exercise, this is shown by calculating \( F(2) \) and \( F(1) \), then finding the difference \( F(2) - F(1) \).