Chapter 3: Problem 5
Differentiate the functions. $$y=x\left(x^{2}+1\right)^{4}$$
Short Answer
Expert verified
The derivative is \( (x^2 + 1)^4 + 8x^2 (x^2 + 1)^3 \).
Step by step solution
01
Identify the Parts of the Function
The function is given by \( y = x (x^2 + 1)^4 \). This function is a product of two functions, where \( u = x \) and \( v = (x^2 + 1)^4 \). We will use the product rule to differentiate the function.
02
State the Product Rule
The product rule states that \( (uv)' = u'v + uv' \). We need to find \( u' \) and \( v' \).
03
Differentiate Each Part
First, find \( u' \). Since \( u = x \), \( u' \) is the derivative of \( x \), which is \( 1 \). Next, we find \( v' \). To differentiate \( v = (x^2 + 1)^4 \), use the chain rule.
04
Apply the Chain Rule
To differentiate \( v = (x^2 + 1)^4 \), let \( w = x^2 + 1 \). Then, \( v = w^4 \). The derivative \( v' \) is \( 4w^3 \cdot w' \). Since \( w = x^2 + 1 \), \( w' = 2x \). Thus, \( v' = 4(x^2 + 1)^3 \cdot 2x \). This simplifies to \( v' = 8x (x^2 + 1)^3 \).
05
Combine Using the Product Rule
Using the product rule, \( y' = u'v + uv' \). Substituting the values we have found, \( y' = 1 \times (x^2 + 1)^4 + x \times 8x (x^2 + 1)^3 \).
06
Simplify the Expression
Simplify the expression: \( y' = (x^2 + 1)^4 + 8x^2 (x^2 + 1)^3 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Product Rule
The \textbf{Product Rule} is a fundamental concept in differentiation, helping determine the derivative of a product of two functions. It works because the change in a product function depends on the changes in both of its component functions. The rule states that for two functions, \(u\) and \(v\), the derivative of their product is given by: \[ (uv)' = u'v + uv' \].
Here, we identified \(u = x\) and \(v = (x^2 + 1)^4\).
First, find the derivative of \(u\), which is straightforward:
Here, we identified \(u = x\) and \(v = (x^2 + 1)^4\).
First, find the derivative of \(u\), which is straightforward:
- \( u = x \)
- \( u' = 1 \)
Chain Rule
The \textbf{Chain Rule} is another critical tool for finding the derivative of composite functions. When you have a function inside another function, the chain rule helps to differentiate it systematically. It can be summarized as: \[ (f(g(x)))' = f'(g(x)) \times g'(x) \].
For our exercise, we needed to differentiate \(v = (x^2 + 1)^4\). To apply the chain rule, we let:
For our exercise, we needed to differentiate \(v = (x^2 + 1)^4\). To apply the chain rule, we let:
- \( w = x^2 + 1 \)
- \( v = w^4 \)
- \( w' = 2x \)
- \( v' = 4w^3 \times w' \)
- \( v' = 4(x^2 + 1)^3 \times 2x \)
- \( v' = 8x (x^2 + 1)^3 \)
Simplifying Derivatives
The final step in differentiation often involves \textbf{Simplifying Derivatives} for clarity and utility. Simplification makes the result easier to interpret and use in subsequent calculations. In our case, after applying the product rule:\[ y' = u'v + uv' \, \text{where} \, u' = 1 \, \text{and} \, v' = 8x (x^2 + 1)^3 \] Combining what we have: \[ y' = 1 \times (x^2 + 1)^4 + x \times 8x (x^2 + 1)^3 \] Then, we simplify this expression further: \[ y' = (x^2 + 1)^4 + 8x^2 (x^2 + 1)^3 \] Now, you have a clear, simplified derivative, which is easier to analyze and use.