Chapter 3: Problem 44
Find the derivatives of the given functions. Assume that \(a, b, c,\) and \(k\) are constants. $$f(x)=\frac{a x+b}{x}$$
Short Answer
Expert verified
The derivative of \( f(x) = \frac{a x + b}{x} \) is \( f'(x) = -\frac{b}{x^2} \).
Step by step solution
01
Identify the Problem
We need to find the derivative of the function \( f(x) = \frac{a x + b}{x} \). This is a rational function, and we will use the quotient rule to find its derivative.
02
Rewrite the Function
Rewrite the function \( f(x) = \frac{a x + b}{x} \) as \( f(x) = a + \frac{b}{x} \) by separating the terms.
03
Differentiate Using Individual Rules
The function is \( f(x) = a + \frac{b}{x} \). Differentiate it term by term: - The derivative of the constant \( a \) is 0.- The derivative of \( \frac{b}{x} \), which is \( b \cdot x^{-1} \), is \( -b \cdot x^{-2} \), or equivalently \(-\frac{b}{x^2}\).
04
Combine the Results
Combine the derivatives of the separated terms: - The derivative \( 0 \) from the constant and - The derivative \( -\frac{b}{x^2} \) from the term \( \frac{b}{x} \).Hence, the derivative of \( f(x) \) is \( f'(x) = -\frac{b}{x^2} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quotient Rule
In calculus, the Quotient Rule is a method used to find the derivative of a function that is the division of two other functions. The general formula for the quotient rule for two differentiable functions, say \(u(x)\) and \(v(x)\), is:\[\left( \frac{u}{v} \right)' = \frac{u'v - uv'}{v^2}\]To apply it effectively:
- The function in the numerator is \(u(x)\), and its derivative is \(u'(x)\).
- The function in the denominator is \(v(x)\), and its derivative is \(v'(x)\).
Rational Function
A rational function is any function which can be expressed as the ratio of two polynomials. It takes the form:\[f(x) = \frac{p(x)}{q(x)}\]where \(p(x)\) and \(q(x)\) are polynomials. The function \(f(x) = \frac{a x + b}{x}\) is an example. Here:
- \(p(x) = a x + b\)
- \(q(x) = x\)
Differentiation
Differentiation is the process of finding the derivative of a function, which represents the rate of change of the function with respect to a variable. When differentiating, two main rules are vital:
- The Power Rule: If \(f(x) = x^n\), then \(f'(x) = nx^{n-1}\).
- The Sum Rule: If \(f(x) = g(x) + h(x)\), then \(f'(x) = g'(x) + h'(x)\).
Constant Function
A constant function is a simple yet powerful concept in calculus. It is a function whose output value is the same, regardless of the input value, typically expressed as \(f(x) = c\) where \(c\) is a constant. A key differentiation rule is:
- The derivative of a constant is always zero.