Chapter 4: Problem 1
Find an antiderivative for each function. Do as many as you can mentally. Check your answers by differentiation. a. \(2 x\) b. \(x^{2}\) c. \(x^{2}-2 x+1\)
Short Answer
Expert verified
The antiderivatives are \( x^2 + C \), \( \frac{1}{3}x^3 + C \), and \( \frac{1}{3}x^3 - x^2 + x + C \).
Step by step solution
01
Understanding the Problem
We need to find the antiderivatives of the given functions. An antiderivative of a function is another function whose derivative is equal to the original function. The general antiderivative includes a constant of integration, denoted as +C.
02
Antiderivative of 2x
To find the antiderivative of the function \( 2x \), we use the power rule for integration: if \( f(x) = ax^n \), then its antiderivative is \( \frac{a}{n+1}x^{n+1} + C \). For \( 2x \), it is equivalent to \( 2x^1 \), so the antiderivative is \( x^2 + C \).
03
Antiderivative of x^2
The function is \( x^2 \). Using the power rule for integration, we increase the power by one and divide by the new power: \( \frac{1}{2+1}x^{2+1} + C = \frac{1}{3}x^{3} + C \).
04
Antiderivative of x^2 - 2x + 1
We find the antiderivative of each term separately: \( \int x^2 \, dx = \frac{1}{3}x^3 + C_1 \), \( \int -2x \, dx = -x^2 + C_2 \), and \( \int 1 \, dx = x + C_3 \). Combining these gives \( \frac{1}{3}x^3 - x^2 + x + C \) where \( C \) is the constant of integration.
05
Checking by Differentiation
We verify by differentiating our antiderivatives. The derivative of \( x^2 + C \) is \( 2x \), the derivative of \( \frac{1}{3}x^3 + C \) is \( x^2 \), and the derivative of \( \frac{1}{3}x^3 - x^2 + x + C \) is \( x^2 - 2x + 1 \). Each matches the original function, confirming our antiderivatives are correct.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Power Rule for Integration
The power rule for integration is a useful tool when computing antiderivatives. It's the counterpart of the power rule in differentiation. Whenever you see a function in the form of \( ax^n \), you can find its antiderivative quite easily.
- Start by increasing the exponent by one. Thus, \( n \) becomes \( n+1 \).
- Then, divide the entire term by this new exponent. This transforms the function to \( \frac{a}{n+1}x^{n+1} \).
Constant of Integration
When finding an antiderivative, it's crucial to remember the constant of integration, noted as \( +C \). This constant accounts for the "family" of possible antiderivatives.
- Differentiating a constant results in zero. Therefore, any constant added during integration does not affect the validation process through differentiation.
- The constant is important because an indefinite integral fundamentally represents all antiderivatives of a function.
Differentiation Check
After finding an antiderivative, performing a differentiation check is an effective way to verify your solution. This involves differentiating your antiderivative to see if you retrieve the original function.
- If successful, the antiderivative is most likely correct. For instance, differentiating \( x^2 + C \) results in \( 2x \), confirming the antiderivative matches the original function.
- Checking with differentiation exposes calculation errors or missed constants. It’s a practical safeguard to ensure that all antiderivatives are correct.