Chapter 48: Problem 8
Die Nullstelle \(x_{0}\) des Polynoms \(p\) vom Grade \(\geqslant 1\) besitzt genau dann die Vielfachheit wenn \(p\left(x_{0}\right)=p^{\prime}\left(x_{0}\right)=\cdots=p^{(e-1)}\left(x_{0}\right)=0\), aber \(p^{(v)}\left(x_{0}\right) \neq 0\) ist.
Short Answer
Expert verified
The root's multiplicity \( e \) is where \( p(x_0), p'(x_0), \ldots, p^{(e-1)}(x_0) = 0 \) and \( p^{(e)}(x_0) \neq 0 \).
Step by step solution
01
Understanding the Problem Statement
The problem is asking about the multiplicity of a root \( x_0 \) of a polynomial \( p \) of degree \( \geq 1 \). The multiplicity is the number \( e \) such that the polynomial and its derivatives up to order \( e-1 \) are zero at \( x_0 \), but the derivative of order \( e \) is not zero at \( x_0 \). This essentially means that \( x_0 \) is a root of multiplicity \( e \).
02
Concept of Multiplicity
For a root of multiplicity \( e \), the polynomial can be expressed in the form \( p(x) = (x - x_0)^e q(x) \), where \( q(x_0) eq 0 \). This implies that the root \( x_0 \) appears \( e \) times in the factorization of the polynomial.
03
Check the Condition
According to the condition given, the root \( x_0 \) satisfies: \( p(x_0) = p'(x_0) = \cdots = p^{(e-1)}(x_0) = 0 \), but \( p^{(v)}(x_0) eq 0 \). This indicates that each derivative up to \( e-1 \) is zero, matching the root's multiplicity. The condition \( p^{(e)}(x_0) eq 0 \) confirms that \( e \) is the root's exact multiplicity.
04
Verify the Final Derivative
The derivative \( p^{(e)}(x_0) eq 0 \) confirms that the first non-zero derivative is of order \( e \), which doesn't happen for derivatives less than \( e \). This final derivative condition is essential to distinguish the root's multiplicity and ensure it doesn't have higher multiplicity.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Roots
In mathematics, a polynomial is an algebraic expression made up of variables and coefficients. The roots of a polynomial are the values for which the polynomial evaluates to zero. For a polynomial function \( p(x) \), a root \( x_0 \) satisfies \( p(x_0) = 0 \). The number of roots a polynomial can have is equal to its degree, though some roots may repeat multiple times.
- A root of a polynomial is where the graph of the polynomial crosses the X-axis.
- Real roots are points where the function intersects with the real number line.
- Complex roots occur in conjugate pairs when the coefficients of the polynomial are real numbers.
Derivatives
Derivatives play a significant role in understanding the behavior of functions, including polynomials. The derivative of a function \( p(x) \), denoted as \( p'(x) \), measures the rate at which the function's value changes as its input changes.
- The first derivative \( p'(x) \) provides information about the slope of the function at any given point.
- Higher-order derivatives (like \( p''(x) \), \( p'''(x) \), etc.) provide further insights into the curvature and the rate of change of the slope.
- In the context of roots, derivatives help us determine the multiplicity, as a root of multiplicity \( e \) will make the first \( e-1 \) derivatives zero.
Polynomial Factorization
Polynomial factorization refers to expressing a polynomial as a product of its factors. For a polynomial with roots \( x_0, x_1, ..., x_n \), factorization helps in breaking it down into simpler multiplied expressions. These factors are usually binomials of the form \( (x-x_i) \), where each root contributes to deciding the multiplicity.
- The factorization process simplifies polynomial equations and helps in solving them analytically.
- Understanding the multiplicity of a root affects how many times a factor \( (x-x_0) \) appears in the factorized form of the polynomial.
- Factorization is essential for integration, finding polynomial limits, and simplifying polynomial expressions in calculus.
Root of a Polynomial
The concept of a "root" in polynomials is central to understanding equations. A root \( x_0 \) of a polynomial \( p(x) \) is a value that makes the polynomial equal zero, i.e., \( p(x_0) = 0 \). Each root can potentially affect the overall behavior and graph of the polynomial.
- Roots can be real or complex, influencing the polynomial’s appearance on a graph and its factorization.
- The multiplicity of a root plays a critical part, determining how the polynomial factors and behaves near the root.
- To find a root, various mathematical techniques like factoring, synthetic division, or using the quadratic formula may be employed.