Chapter 3: Problem 18
Find the derivative of the function. \(f(x)=\frac{\left(x^{2}+1\right)^{2}}{\left(x^{4}+1\right)^{4}}\)
Short Answer
Expert verified
The derivative is \( f'(x) = \frac{4x(x^2 + 1)(x^4 + 1)^3(-3x^4 - 4x^2 + 1)}{(x^4 + 1)^8} \).
Step by step solution
01
Identify the quotient rule
The given function is a fraction of the form \( \frac{u(x)}{v(x)} \) where \( u(x) = (x^2 + 1)^2 \) and \( v(x) = (x^4 + 1)^4 \). To find the derivative \( f'(x) \), we will apply the quotient rule: \( \left( \frac{u}{v} \right)' = \frac{v \cdot u' - u \cdot v'}{v^2} \).
02
Find the derivative of the numerator
The numerator of the function is \( u(x) = (x^2 + 1)^2 \). We use the chain rule for differentiation: \( u'(x) = 2(x^2 + 1) \cdot (2x) = 4x(x^2 + 1) \).
03
Find the derivative of the denominator
The denominator of the function is \( v(x) = (x^4 + 1)^4 \). Again using the chain rule: \( v'(x) = 4(x^4 + 1)^3 \cdot (4x^3) = 16x^3(x^4 + 1)^3 \).
04
Apply the quotient rule
Substitute \( u(x) \), \( u'(x) \), \( v(x) \), and \( v'(x) \) into the quotient rule formula:\[f'(x) = \frac{(x^4 + 1)^4 \cdot 4x(x^2 + 1) - (x^2 + 1)^2 \cdot 16x^3(x^4 + 1)^3}{((x^4 + 1)^4)^2}\]
05
Simplify the expression
Factor out common terms from the numerator: \[f'(x) = \frac{4x(x^2 + 1)(x^4 + 1)^3 \left((x^4 + 1) - 4x^2(x^2 + 1)\right)}{(x^4 + 1)^8}\]Further simplify:\[(x^4 + 1) - 4x^2(x^2 + 1) = x^4 + 1 - 4x^4 - 4x^2 = -3x^4 - 4x^2 + 1\]
06
Write the final simplified derivative
The final derivative is:\[f'(x) = \frac{4x(x^2 + 1)(x^4 + 1)^3(-3x^4 - 4x^2 + 1)}{(x^4 + 1)^8}\]This can be further simplified, but for clarity, this is the expression of \( f'(x) \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quotient Rule
When differentiating a function that is a fraction, the quotient rule is an essential tool. It is used when you have a function in the form \( \frac{u(x)}{v(x)} \), where both the numerator \( u(x) \) and the denominator \( v(x) \) are functions of the same variable. This rule helps you find the derivative by applying the formula: \[ \left( \frac{u}{v} \right)' = \frac{v \cdot u' - u \cdot v'}{v^2} \]
- First, find the derivatives of the numerator \( u'(x) \) and the denominator \( v'(x) \).
- Next, multiply the denominator function \( v(x) \) by the derivative of the numerator \( u'(x) \).
- Then, subtract the result of the numerator \( u(x) \) times the derivative of the denominator \( v'(x) \).
- Finally, divide the entire expression by the square of the denominator function \( v(x)^2 \).
Chain Rule
Differentiating functions that are nested within each other requires the chain rule. It is particularly useful when dealing with composite functions, allowing you to find the derivative of a function that is, literally, a function within a function. For a composite function \( Y = f(g(x)) \), the derivative \( Y' \) can be found using the formula: \[ Y' = f'(g(x)) \cdot g'(x) \]
- First, identify the outer function \( f \) and the inner function \( g \).
- Take the derivative of the outer function, \( f'(g(x)) \).
- Then, multiply it by the derivative of the inner function, \( g'(x) \).
Simplification
After finding the derivative using the quotient and chain rules, you often face a complex expression. Simplification is the process of reducing this expression to its simplest or most intuitive form. Here is how you can approach it:
- Factor out common terms, which can reduce the complexity of the expression.
- Combine like terms, which simplifies the arithmetic operations involved.
- Break down expressions, sometimes by rewriting and reorganizing them with basic algebraic identities.