Chapter 2: Problem 35
If \(x-c\) is a factor of order \(m\) of the polynomial \(f(x)\) of degree
\(n(1
Short Answer
Expert verified
Option (b) \(f^{m-1}(x)\) is correct.
Step by step solution
01
Understand the problem
We need to determine if \( x=c \) is a root of any of the expressions provided when \( x-c \) is a factor of order \( m \) of the polynomial \( f(x) \).
02
Review Factor Theorem
According to the factor theorem, if \( x-c \) is a factor of \( f(x) \), then \( f(c) = 0 \). For a factor \( (x-c)^m \), \( f(c) = f'(c) = ... = f^{(m-1)}(c) = 0 \). This implies \( x=c \) is a root of all derivatives up to \( f^{(m-1)}(x) \).
03
Determine the order of derivative
Since \( x-c \) is a factor of order \( m \), \( x=c \) is not a root of \( f^m(x) \), because \( f^{(m)}(c) eq 0 \). Hence, \( x = c \) is a root of \( f^{(m-1)}(x) \), as \( f^{(m-1)}(c) = 0 \).
04
Conclusion
Based on the above reasoning, \( x=c \) is a root of \( f^{(m-1)}(x) \), thus the answer is option (b).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Roots of Polynomials
Finding the roots of a polynomial is a fundamental concept in algebra. It involves discovering the values of \( x \) that turn the polynomial into zero. These values, known as roots or zeros, tell us where the graph of the polynomial will intersect the x-axis. The Factor Theorem provides an invaluable strategy here: if \( (x-c) \) is a factor of \( f(x) \), then \( c \) is a root. However, when dealing with factors like \( (x-c)^m \), the situation becomes more complex. In such cases, the root \( x = c \) is known as a root of multiplicity \( m \), which means it appears \( m \) times as a root. For instance, in our scenario, since \( (x-c) \) is a factor of order \( m \), it implies that \( x=c \) is a root for all derivatives of \( f(x) \) up to \( f^{(m-1)}(x) \). In summary, understanding how the roots function in relation to their factors is crucial for solving polynomial equations effectively.
Derivatives of Polynomials
Derivatives are a key tool in calculus used to understand the rate of change of functions. For polynomials, derivatives help in understanding their behavior and structure. The derivative of a polynomial function describes how its slope changes, which helps in identifying peaks, troughs, and inflection points on its graph.In the context of the Factor Theorem and polynomial roots, derivatives play a critical role. When a polynomial \( f(x) \) has a factor like \( (x-c)^m \), derivatives reveal how the root \( x = c \) behaves across different derivatives of the polynomial. Specifically, it is known that if \( (x-c) \) is a factor of order \( m \), then the derivatives up to \( f^{(m-1)}(x) \) will have \( x=c \) as a root, because all these derivatives will equal zero when evaluated at \( c \). Meanwhile, the \( m \)th derivative, \( f^m(x) \), will not necessarily have the same root at \( x=c \). This understanding helps in pinpointing specific characteristics about the nature of the polynomial around its roots.
Order of a Factor
The term "order of a factor" refers to the number of times a factor is repeated in the polynomial. When \( (x-c)^m \) is a factor of a polynomial, it means \( x = c \) is a root of multiplicity \( m \). This multiplicity affects the polynomial's behavior significantly.Factors of higher order indicate the presence of a "flat" section on the polynomial's graph at the root. Specifically, this flat section occurs because both the polynomial and its lower-order derivatives will evaluate to zero at that root. This is seen where both \( f(x) \), \( f'(x) \), and so on, up to \( f^{(m-1)}(x) \), have \( x = c \) as a zero, but \( f^m(x) \) generally does not unless \( m=n \).Therefore, understanding the order of a factor helps in graphing polynomials accurately and leveraging derivatives to gain insights into its characteristics, like inflection points or changes in concavity around its roots.