Chapter 1: Problem 72
For each function, find and simplify \(\frac{f(x+h)-f(x)}{h} .\) (Assume \(\left.h \neq 0 .\right)\) (See instructions on previous page.) $$ f(x)=\frac{3}{x} $$
Short Answer
Expert verified
The simplified form is \( \frac{-3}{x(x+h)} \).
Step by step solution
01
Understanding the Difference Quotient
The difference quotient of a function \( f(x) \) is given by the formula: \[\frac{f(x+h) - f(x)}{h},\] where \( h eq 0 \). We need to compute this for the function \( f(x) = \frac{3}{x} \).
02
Substitute \( f(x+h) \) and \( f(x) \)
Substitute \( x+h \) into the function: \( f(x+h) = \frac{3}{x+h} \).Now, substitute \( f(x) \): \( f(x) = \frac{3}{x} \).
03
Apply the Difference Quotient Formula
Substitute \( f(x+h) \) and \( f(x) \) into the difference quotient formula: \[\frac{\frac{3}{x+h} - \frac{3}{x}}{h}\]
04
Find a Common Denominator
To simplify the expression \( \frac{\frac{3}{x+h} - \frac{3}{x}}{h} \), find a common denominator for the fractions within the numerator, which is \( x(x+h) \). Rewrite each fraction as:\[\frac{3x}{x(x+h)} - \frac{3(x+h)}{x(x+h)}\]
05
Simplify the Numerator
Simplify the expression by subtracting the numerators: \[\frac{3x - 3(x+h)}{x(x+h)} = \frac{3x - 3x - 3h}{x(x+h)} = \frac{-3h}{x(x+h)}\]
06
Cancel \( h \)
Substitute the simplified expression back into the difference quotient:\[\frac{-3h}{x(x+h)h} = \frac{-3}{x(x+h)}\]Canceling \( h \) in the numerator and denominator provides the final simplified form.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Simplification
Function simplification is all about rewriting mathematical expressions in a more concise or useful way, which often makes solving calculus problems easier. In this exercise, we are focusing on simplifying the difference quotient of the function \( f(x) = \frac{3}{x} \). This involves tactical algebraic manipulations.
Initially, we put \( x + h \) into our function, getting \( f(x + h) = \frac{3}{x + h} \). Then we apply the difference quotient formula: \( \frac{f(x+h) - f(x)}{h} \). The simplified form requires carefully working through algebraic steps, including handling complex fractions.
Initially, we put \( x + h \) into our function, getting \( f(x + h) = \frac{3}{x + h} \). Then we apply the difference quotient formula: \( \frac{f(x+h) - f(x)}{h} \). The simplified form requires carefully working through algebraic steps, including handling complex fractions.
Common Denominator
When dealing with fractions, especially in calculus, finding a common denominator is a crucial step. It allows for smooth subtraction or addition of fractions, which is often necessary for solving difference quotients.
For the expression \( \frac{\frac{3}{x + h} - \frac{3}{x}}{h} \), the common denominator is \( x(x+h) \). This means rewriting each fraction to have this same denominator:
For the expression \( \frac{\frac{3}{x + h} - \frac{3}{x}}{h} \), the common denominator is \( x(x+h) \). This means rewriting each fraction to have this same denominator:
- \( \frac{3}{x+h} \) becomes \( \frac{3x}{x(x+h)} \)
- \( \frac{3}{x} \) becomes \( \frac{3(x+h)}{x(x+h)} \)
Fraction Subtraction
Subtracting fractions is another essential part of simplifying the difference quotient. Once the fractions are rewritten with a common denominator, you can subtract them easily.In our problem, after establishing the common denominator \( x(x+h) \), we subtract the numerators:
- \( 3x - 3(x+h) \)
Calculus Problems
The difference quotient is central to understanding calculus problems, specifically derivatives. In this problem, the simplified difference quotient function represents a preliminary step toward finding the derivative of \( f(x) = \frac{3}{x} \).Cancelling terms is a common goal: after subtracting, we reach \( \frac{-3h}{x(x+h)} \). From this, the \( h \) cancels each other out when divided by the denominator's \( h \):
- This results in \( \frac{-3}{x(x+h)} \)