Chapter 1: Problem 82
Complete the following for the given \(f(x)\) (a) Find \(f(x+h)\) (b) Find the difference quotient of \(f\) and simplify. $$ f(x)=1-x^{3} $$
Short Answer
Expert verified
(a) \( f(x+h) = 1 - x^3 - 3x^2h - 3xh^2 - h^3 \), (b) \( -3x^2 - 3xh - h^2 \)
Step by step solution
01
Substitute (x + h) into f(x)
To find \(f(x+h)\), substitute \(x+h\) into the function \(f(x) = 1 - x^3\).\[ f(x+h) = 1 - (x+h)^3 \]
02
Expand the Binomial (x + h)^3
Use the binomial theorem to expand \((x+h)^3\):\[(x+h)^3 = x^3 + 3x^2h + 3xh^2 + h^3\]Substitute back into the function:\[ f(x+h) = 1 - (x^3 + 3x^2h + 3xh^2 + h^3) \]
03
Simplify Expression for f(x + h)
Simplify the expression by distributing the negative sign:\[ f(x+h) = 1 - x^3 - 3x^2h - 3xh^2 - h^3 \]
04
Set Up the Difference Quotient
The difference quotient for \(f(x)\) is given by:\[ \frac{f(x+h) - f(x)}{h} \]
05
Substitute and Simplify Difference Quotient
Substitute \(f(x+h)\) and \(f(x) = 1 - x^3\) into the difference quotient:\[ \frac{1 - x^3 - 3x^2h - 3xh^2 - h^3 - (1 - x^3)}{h} \]Simplify:\[ \frac{-3x^2h - 3xh^2 - h^3}{h} \]
06
Simplify by Canceling h
Factor out \(h\) from the numerator and cancel it with the denominator:\[ \frac{h(-3x^2 - 3xh - h^2)}{h} = -3x^2 - 3xh - h^2 \]
07
Find the Simplified Difference Quotient
The simplified difference quotient is:\[ -3x^2 - 3xh - h^2 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Functions
Polynomial functions are mathematical expressions that involve the sum of powers of a variable, each multiplied by a coefficient. In simple terms, they are functions that consist of terms involving variables raised to whole number exponents and their respective coefficients. Here are some key points to remember about polynomial functions:
- The general form of a polynomial function is: \( f(x) = a_nx^n + a_{n-1}x^{n-1} + \ldots + a_1x + a_0 \).
- The highest exponent of the variable determines the degree of the polynomial.
- Each term consists of a coefficient and a variable raised to an exponent, like \(a_nx^n\).
Binomial Expansion
Binomial expansion is an essential part of working with polynomial functions, especially when dealing with expressions of the form \((x+h)^n\). The binomial theorem gives us a way to expand these expressions efficiently:
- It states that \((x + y)^n\) can be expanded into a series of terms in the form of \(a \cdot b\), where each term is a combination of the original variables raised to different powers.
- For example, \((x+h)^3 = x^3 + 3x^2h + 3xh^2 + h^3\).
- The coefficients of the expanded terms correspond to the binomial coefficients, found in Pascal's Triangle or by the formula for combinations \(\binom{n}{k}\).
Function Simplification
Simplifying functions is a crucial step in calculus and algebra that involves rewriting expressions in a simpler or reduced form without changing their value. This process is important as it makes equations easier to handle and interpret.Here are the steps typically involved in function simplification:
- Substitution: Replace variables or constants as instructed, like finding \(f(x+h)\) by substituting \(x+h\) into \(f(x)\).
- Expansion: Use techniques such as the binomial theorem to expand complex expressions into their expanded forms.
- Distribution: Apply distribution laws to remove parentheses and combine like terms, simplifying the function further.
- Reduction: Cancel common terms or factors across the numerator and denominator, reducing the expression to its simplest form.