Chapter 3: Problem 16
Find the first derivative. $$ g(w)=\frac{(w-1)(w-3)}{(w+1)(w+3)} $$
Short Answer
Expert verified
The first derivative is \( g'(w) = \frac{4w^3 + 2w^2 - 24w}{((w+1)(w+3))^2} \).
Step by step solution
01
Identify Derivative Rule
To find the derivative of the function \(g(w) = \frac{(w-1)(w-3)}{(w+1)(w+3)}\), we'll use the quotient rule for derivatives. The quotient rule states that if you have a function \( \frac{u(w)}{v(w)} \), its derivative is \( \frac{u'(w)v(w) - u(w)v'(w)}{(v(w))^2} \). Identify \( u(w) \) as \((w-1)(w-3)\) and \( v(w) \) as \((w+1)(w+3)\).
02
Find Derivative of u(w)
The function \( u(w) = (w-1)(w-3) \) can be expanded to \( w^2 - 4w + 3 \). Find the derivative, \( u'(w) = \frac{d}{dw}(w^2 - 4w + 3) = 2w - 4 \).
03
Find Derivative of v(w)
Similarly, the function \( v(w) = (w+1)(w+3) \) can be expanded to \( w^2 + 4w + 3 \). Find the derivative, \( v'(w) = \frac{d}{dw}(w^2 + 4w + 3) = 2w + 4 \).
04
Apply Quotient Rule
Using the quotient rule, the derivative of \( g(w) \) is given by: \[g'(w) = \frac{(2w - 4)(w+1)(w+3) - (w-1)(w-3)(2w + 4)}{((w+1)(w+3))^2}\].
05
Simplify the Expression
First, expand each term in the numerator. Calculate \((2w - 4)(w+1)(w+3)\) and \((w-1)(w-3)(2w + 4)\), then simplify:- For \((2w - 4)(w+1)(w+3)\): Expand stepwise, resulting in \(2w^3 + 10w^2 + 12w - 12\).- For \((w-1)(w-3)(2w + 4)\): Expand stepwise, resulting in \(2w^3 - 8w^2 - 12w + 12\).Subtract these expressions to simplify.
06
Final Simplification
After simplification, combine like terms to obtain a simplified expression for the numerator. Check and simplify further if needed. Then provide the final expression for \( g'(w) \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quotient Rule
The quotient rule is a powerful tool in calculus used to find derivatives of functions that are given as a ratio of two other functions. If you have a function in the form \( \frac{u(w)}{v(w)} \), the derivative \( \frac{d}{dw}\left( \frac{u(w)}{v(w)} \right) \) is calculated using the formula:
- \( \frac{u'(w)v(w) - u(w)v'(w)}{(v(w))^2} \)
- Differentiate the numerator \( u(w) \) to get \( u'(w) \)
- Differentiate the denominator \( v(w) \) to get \( v'(w) \)
- Multiply \( u'(w) \) by \( v(w) \) and \( u(w) \) by \( v'(w) \)
- Subtract the second product from the first
- Divide by the square of the denominator \( (v(w))^2 \)
Derivative of a Polynomial
A polynomial is an algebraic expression consisting of variables and coefficients, involving only the operations of addition, subtraction, multiplication, and non-negative integer exponents. Finding the derivative of a polynomial is straightforward. You apply basic rules which simplify down to:
- The power rule: If \( f(x) = x^n \), then \( f'(x) = nx^{n-1} \)
- Sum rule: The derivative of a sum is the sum of the derivatives
- Constant rule: The derivative of a constant is zero
- \( \frac{d}{dw}(w^2) = 2w \)
- \( \frac{d}{dw}(-4w) = -4 \)
- \( \frac{d}{dw}(3) = 0 \)
Simplification of Expressions
Simplifying mathematical expressions is essential in calculus to make outcomes readable and comprehensible. After deriving or transforming expressions, complexity might arise, which means simplifying is a necessary step. Here's why simplification matters and how it’s done:
- Reduce expressions by combining like terms and eliminating redundant components.
- Avoid unwieldy numbers by canceling out terms wherever possible, provided the operations are valid.
- Simplified expressions not only look neater but are also easier to interpret and apply in further mathematical operations.