Chapter 2: Problem 52
Simplify the difference quotient \(\frac{f(x+h)-f(x)}{h}\) if \(h \neq 0\). $$f(x)=x^{3}-2$$
Short Answer
Expert verified
The simplified difference quotient is \(3x^2 + 3xh + h^2\).
Step by step solution
01
Write down the difference quotient
The difference quotient is given by \( \frac{f(x+h)-f(x)}{h} \). We will substitute \( f(x) = x^3 - 2 \) into this formula.
02
Compute \( f(x+h) \)
Find \( f(x+h) \) by substituting \( x+h \) into the function: \( f(x+h) = (x+h)^3 - 2 \).
03
Expand \( (x+h)^3 \)
Expand \( (x+h)^3 \) using the binomial theorem: \((x+h)^3 = x^3 + 3x^2h + 3xh^2 + h^3 \).
04
Substitute and simplify \( f(x+h) - f(x) \)
Substitute \( f(x+h) \) and \( f(x) \) into the difference: \(((x+h)^3 - 2) - (x^3 - 2) = x^3 + 3x^2h + 3xh^2 + h^3 - x^3 \). This simplifies to \( 3x^2h + 3xh^2 + h^3 \).
05
Divide by \( h \)
Substitute the expression obtained in Step 4 into the difference quotient and divide each term by \( h \): \( \frac{3x^2h + 3xh^2 + h^3}{h} = 3x^2 + 3xh + h^2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Binomial Theorem
The binomial theorem is a powerful tool for expanding expressions that are raised to a power. In this particular exercise, we use it to expand \((x+h)^3\). The theorem states that for any positive integer \(n\), \((a+b)^n\) can be expanded as:
- \((a+b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k}b^k\)
- \(x^3 + 3x^2h + 3xh^2 + h^3\)
Polynomial Functions
Polynomial functions are expressions that involve variables raised to whole number powers. The most basic form of a polynomial function is \(f(x) = ax^n + bx^{n-1} + \cdots + z\), where each term is a product of a coefficient and a variable raised to a power.
In this exercise, the function \(f(x) = x^3 - 2\) is a cubic polynomial, meaning its highest degree is 3. Polynomial functions have distinct properties that make them straightforward to manipulate mathematically, such as:
In this exercise, the function \(f(x) = x^3 - 2\) is a cubic polynomial, meaning its highest degree is 3. Polynomial functions have distinct properties that make them straightforward to manipulate mathematically, such as:
- Being smooth and continuous.
- Having a finite number of roots.
- Being easy to differentiate and integrate.
Simplification of Expressions
Simplifying expressions is a fundamental skill in algebra and calculus. It involves reducing expressions to their simplest form. In this exercise, simplifying \(f(x+h) - f(x)\) means canceling common terms and factoring where possible.
Once we've expanded \((x+h)^3\) and substituted into the difference \(f(x+h) - f(x)\), we end up with \(x^3 + 3x^2h + 3xh^2 + h^3 - x^3\). Simplification occurs as follows:
Once we've expanded \((x+h)^3\) and substituted into the difference \(f(x+h) - f(x)\), we end up with \(x^3 + 3x^2h + 3xh^2 + h^3 - x^3\). Simplification occurs as follows:
- Canceling out \(x^3\) since it's in both \(f(x+h)\) and \(f(x)\).
- Combining the remaining terms: \(3x^2h + 3xh^2 + h^3\).
Precalculus
Precalculus bridges the gap between algebra and calculus. It includes a variety of topics necessary for understanding calculus concepts, such as functions, complex numbers, and limits. In this exercise, understanding precalculus means being proficient with:
- Manipulating functions like polynomials.
- Expanding expressions accurately, such as using the binomial theorem.
- Simplifying complex algebraic expressions to reveal underlying patterns.