What is a root with multiplicity?

In summary, the concept of a root with multiplicity refers to the number of times a particular value is a root of a polynomial. If (x - a) is a repeated factor of a polynomial f(x), then a is considered a root with multiplicity k, where k is the number of times the factor (x - a) appears in f(x). This can be helpful in understanding the behavior and properties of polynomials.
  • #1
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I'm reading a chapter on recurrence relations and they have a problem with the phrase: ...if r is a root with multiplicity 2. What does it mean for a root to have multiplicity? This is the first time I've heard of this and the book assumes I would know what they mean already.
 
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  • #2
If f(x) is a polynomial, and a is a root of f, then (x - a) is a factor of f(x).

If (x - a) is a repeated factor, that is (x - a)^k is a factor of f(x), then a is a root with multiplicity k.
 
  • #3
I'd figured it be something like that. Thanks for clearing that up.
 

Related to What is a root with multiplicity?

1. What are roots with multiplicity?

Roots with multiplicity refer to the number of times a particular value appears as a solution to a polynomial equation. For example, if the equation (x-2)(x+3) = 0 has two solutions, x=2 and x=-3, then each root has a multiplicity of 1. However, if the equation (x-2)^2 = 0 has only one solution, x=2, then the root has a multiplicity of 2.

2. How do you determine the multiplicity of a root?

To determine the multiplicity of a root, you must first factor the polynomial equation. Then, count the number of times the root appears as a factor. This number is the multiplicity of the root. Alternatively, if you have a graph of the equation, the multiplicity of a root is equal to the number of times the graph touches or crosses the x-axis at that particular root.

3. What is the significance of roots with multiplicity?

The multiplicity of a root can provide valuable information about the behavior of a polynomial equation. For example, if a root has an odd multiplicity, the graph of the equation will cross the x-axis at that root. If a root has an even multiplicity, the graph will touch but not cross the x-axis at that root. Additionally, the multiplicity of a root can affect the number of solutions to the equation and the shape of the graph.

4. Can a root have a multiplicity of 0?

Yes, a root can have a multiplicity of 0. This means that the root does not appear as a solution to the polynomial equation. In other words, the equation has no x-intercept at that particular value. This can occur when a factor in the polynomial is raised to a power of 0, making the term equal to 1 and no longer contributing to the solution.

5. How do you handle roots with multiplicity when graphing a polynomial equation?

When graphing a polynomial equation, it is important to consider the multiplicity of each root. For each root with an odd multiplicity, the graph will cross the x-axis at that root. For each root with an even multiplicity, the graph will touch but not cross the x-axis at that root. Additionally, the shape of the graph near a root with a multiplicity greater than 1 will be flatter compared to a root with a multiplicity of 1. This can help in accurately sketching the graph of a polynomial equation.

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