Chapter 4: Problem 50
Differentiate with respect to the independent variable. \(f(x)=\frac{1-4 x^{3}}{1-x}\)
Short Answer
Expert verified
The derivative is \(f'(x) = \frac{-12x^2 + 8x^3 + 1}{(1 - x)^2}\).
Step by step solution
01
Identify the Function Type
The function given is a rational function, where the numerator and denominator are polynomials: \(f(x) = \frac{1 - 4x^3}{1 - x}\). We will need to use the quotient rule to differentiate this rational function.
02
Recall the Quotient Rule
The quotient rule for differentiation states that if you have a function \(f(x) = \frac{g(x)}{h(x)}\), then its derivative \(f'(x)\) is given by \(f'(x) = \frac{g'(x) h(x) - g(x) h'(x)}{(h(x))^2}\). Here, \(g(x) = 1 - 4x^3\) and \(h(x) = 1 - x\).
03
Differentiate the Numerator and Denominator
Differentiate \(g(x) = 1 - 4x^3\):- \(g'(x) = 0 - 12x^2 = -12x^2\).Differentiate \(h(x) = 1 - x\):- \(h'(x) = 0 - 1 = -1\).
04
Apply the Quotient Rule
Substitute the derivatives and original functions into the quotient rule formula:\[ f'(x) = \frac{(-12x^2)(1 - x) - (1 - 4x^3)(-1)}{(1 - x)^2}\]Now simplify this expression.
05
Simplify the Expression
Simplify the numerator step by step:\[\begin{aligned}& (-12x^2)(1 - x) = -12x^2 + 12x^3, \& (1 - 4x^3)(-1) = -1 + 4x^3.\end{aligned}\]Combine these results:\[f'(x) = \frac{-12x^2 + 12x^3 + 1 - 4x^3}{(1 - x)^2}\]Next, combine like terms:\[f'(x) = \frac{-12x^2 + 8x^3 + 1}{(1 - x)^2}\].
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Differentiation
Differentiation is a fundamental concept in calculus, focusing on the rate at which things change. It's about finding a function's derivative, which is like the speed of change at any given point. By differentiating, we gain insight into the slope of a function at any point on its curve. This crucial tool helps solve real-world problems involving rates of change, such as velocity in physics or growth rates in biology. For a function represented as \(f(x)\), its derivative, noted as \(f'(x)\), tells us how \(f(x)\) changes as \(x\) changes.
Let's break down the differentiation process using the function \(f(x) = \frac{1 - 4x^3}{1 - x}\). This function is a rational function, meaning it needs the quotient rule. Remember that the quotient rule is vital for differentiating when you have two functions divided by each other:
Let's break down the differentiation process using the function \(f(x) = \frac{1 - 4x^3}{1 - x}\). This function is a rational function, meaning it needs the quotient rule. Remember that the quotient rule is vital for differentiating when you have two functions divided by each other:
- We identify \(g(x) = 1 - 4x^3\)
- and \(h(x) = 1 - x\).
- Then differentiate each to get \(g'(x) =-12x^2\) and \(h'(x) = -1\).
Rational Function
A rational function is a type of function represented as the ratio of two polynomials. Think of a fraction where the top (numerator) and bottom (denominator) are polynomial expressions. The rational function form is \(f(x) = \frac{g(x)}{h(x)}\), where both \(g(x)\) and \(h(x)\) are polynomials.
In our example, \(f(x) = \frac{1 - 4x^3}{1 - x}\), you see clearly that the function is rational since both the numerator, \(1 - 4x^3\), and the denominator, \(1 - x\), are polynomials. Rational functions have unique characteristics:
In our example, \(f(x) = \frac{1 - 4x^3}{1 - x}\), you see clearly that the function is rational since both the numerator, \(1 - 4x^3\), and the denominator, \(1 - x\), are polynomials. Rational functions have unique characteristics:
- They can have vertical asymptotes, which occur where the denominator is zero (meaning undefined).
- Simplifying them often helps gain insight into their behavior.
- Problems involving rational functions frequently require tools such as the quotient rule for differentiation.
Polynomial Functions
Polynomial functions are the building blocks of many complex functions, recognizable by their form: \(a_nx^n + a_{n-1}x^{n-1} + \ldots + a_1x + a_0\), where each \(a_i\) represents a constant coefficient, and the highest power \(n\) is a non-negative integer. Each term is a product of a coefficient and a variable raised to an exponent.
In the differentiation exercise, you encounter polynomial functions in both the numerator \(1 - 4x^3\) and the denominator \(1 - x\). Here, these functions dictate the behavior of their rational counterpart. Understanding the properties of polynomial functions helps immensely:
In the differentiation exercise, you encounter polynomial functions in both the numerator \(1 - 4x^3\) and the denominator \(1 - x\). Here, these functions dictate the behavior of their rational counterpart. Understanding the properties of polynomial functions helps immensely:
- Easy to differentiate because the power rule applies: \(\frac{d}{dx}[x^n] = nx^{n-1}\).
- Simple to manipulate and combine, making them foundational in calculus.
- Understanding how they behave, with respect to slope and curvature, is crucial for analyzing the rational functions they form.