Chapter 25: Problem 46
Solve the given problems. In Exercises \(41-46\) explain your answers. Is \(\int x^{-2} d x=-\frac{1}{3} x^{-3}+C ?\)
Short Answer
Expert verified
No, the correct integral is \( -\frac{1}{x} + C \).
Step by step solution
01
Recall the Power Rule for Integration
The power rule for integration states that \( \int x^n \, dx = \frac{x^{n+1}}{n+1} + C \), where \( n eq -1 \). This allows us to integrate functions in the form of \( x^n \) by increasing the exponent by one and dividing by the new exponent.
02
Apply the Power Rule to Integrate
Given the integral \( \int x^{-2} \, dx \), apply the power rule: the exponent \( n = -2 \).According to the power rule, gain the new exponent by adding 1: \( n+1 = -2+1 = -1 \).Thus, the integral becomes:\[ \int x^{-2} \, dx = \frac{x^{-1}}{-1} + C = -x^{-1} + C = -\frac{1}{x} + C \]
03
Compare to Given Expression
The question asks if \( \int x^{-2} \, dx = -\frac{1}{3}x^{-3} + C \).We have calculated \( \int x^{-2} \, dx = -\frac{1}{x} + C \), which is not the same as \(-\frac{1}{3}x^{-3} + C \).The expressions are different, meaning the provided solution in the question is incorrect.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Calculus Problem Solving
When tackling calculus problems, it's essential to approach each exercise with a clear understanding of the problem's requirements and a strategic plan. Calculus can often seem daunting due to its abstract nature, but following a systematic process can make problem-solving more manageable.
- **Read the Problem Carefully**: Start by carefully interpreting what the exercise demands. Here, we aim to verify if a specific integral \(\int x^{-2} \, dx\) equals a given expression.
- **Identify Known Formulas and Rules**: Have a clear recall of integration rules, such as the Power Rule for Integration, which we used here. Knowing these formulas inside out is crucial.
- **Apply Logical Steps**: Use logic and the right strategy to apply these rules correctly. Formulate the solution by methodically applying known mathematical principles.
- **Check the Solution**: After solving, compare the calculated result to the expected one to ensure accuracy. If there’s a mismatch, reevaluate the steps to find discrepancies.
Integration Techniques
Integration techniques are vital tools in calculus for determining the area under curves, among other applications. The Power Rule is a fundamental technique used to integrate power functions of the form \(x^n\).
- **Understand the Power Rule**: The Power Rule states \(\int x^n \, dx = \frac{x^{n+1}}{n+1} + C\) when \(n eq -1\). This simple adjustment of the exponent and coefficient is fundamental for evaluating integrals involving power functions.
- **Apply the Rule**: For example, given \(\int x^{-2} \, dx\):
- Identify \(n = -2\).
- Apply \(n+1 = -2+1 = -1\) to adjust the exponent.
- Calculate the integral, resulting in \(\int x^{-2} \, dx = -\frac{1}{x} + C\).
- **Avoid Common Mistakes**: Always remember that this rule cannot be used when \(n = -1\) due to division by zero. For \(x^{-1}\), the integral is \(\ln|x| + C\).
Evaluating Integrals
Evaluating integrals involves understanding both the function you are integrating and the proper application of integration techniques to achieve an accurate result.
- **Set Up the Integral**: Carefully determine the integral form. With \(\int x^{-2} \, dx\), we are handling a basic power function suitable for the Power Rule.
- **Perform Integration Accurately**: Methodically apply the correct rules. As in our example, using the Power Rule provided:
Increase the exponent and divide by the new power, resulting in \(\int x^{-2} \, dx = -\frac{1}{x} + C\). - **Interpret the Result**: Once evaluated, ensure that the integral expression aligns with or challenges the initial hypothesis. In this exercise, comparing \(-\frac{1}{x} + C\) with the given \(-\frac{1}{3}x^{-3} + C\) helped affirm that the proposed solution was incorrect.
- **Remain Critical**: Always cross-check your result against provided answers or expected outcomes to verify precision.