Math Problem Statement

Find an equation for the graph of the degree
5 polynomial function shown below. Leave the function in factored form.

A polynomial function on a coordinate plane. A coordinate plane has a horizontal axis labeled from negative 3 to 4 in increments of 1 and a vertical axis labeled from negative 14 to 38 in increments of 2. From left to right, a curve labeled f falls passing through left-parenthesis negative 2.5 comma 24 right-parenthesis to a local minimum at left-parenthesis negative 2 comma 0 right-parenthesis, rises to maximum at left-parenthesis negative 0.4 comma 35.5 right-parenthesis, and falls passing through left-parenthesis 0 comma 32 right-parenthesis, left-parenthesis 2 comma 0 right-parenthesis, and left-parenthesis 2.5 comma negative 2 right-parenthesis. All coordinates are approximate.

Solution

To find the equation of a degree 5 polynomial function given the described graph, we can follow these steps:

Step 1: Identify the roots

From the description, we know the polynomial passes through the points (0,32)(0, 32), (2,0)(2, 0), and (2.5,2)(2.5, -2). Specifically, we can identify the roots of the function where the graph crosses the x-axis.

  • The root at x=2x = 2 has multiplicity 2 because the graph touches the x-axis at x=2x = 2 and doesn't cross it (it has a local minimum there).
  • The root at x=2x = -2 is also a root since the graph touches the x-axis there, suggesting multiplicity 2.

Thus, the roots of the polynomial are:

  • x=2x = -2 with multiplicity 2.
  • x=2x = 2 with multiplicity 2.
  • There is another root near x=0.4x = -0.4, as we can see from the description of the graph reaching a local maximum there. We can approximate it as x=0.4x = -0.4, suggesting it has multiplicity 1.

Step 2: Construct the polynomial in factored form

We now know the polynomial must include these factors:

  • A factor of (x+2)2(x + 2)^2 for the root at x=2x = -2 (multiplicity 2).
  • A factor of (x2)2(x - 2)^2 for the root at x=2x = 2 (multiplicity 2).
  • A factor of (x+0.4)(x + 0.4) for the root near x=0.4x = -0.4.

Therefore, the polynomial can be written as: f(x)=a(x+2)2(x2)2(x+0.4)f(x) = a(x + 2)^2(x - 2)^2(x + 0.4) where aa is a constant that will adjust the vertical stretch/compression.

Step 3: Use known points to find aa

We are given that the graph passes through the point (2.5,24)(-2.5, 24). This means that when x=2.5x = -2.5, f(x)=24f(x) = 24. We substitute x=2.5x = -2.5 into the equation to solve for aa:

24=a(2.5+2)2(2.52)2(2.5+0.4)24 = a(-2.5 + 2)^2(-2.5 - 2)^2(-2.5 + 0.4)

Now, calculate the values: (2.5+2)=0.5,(2.52)=4.5,(2.5+0.4)=2.1(-2.5 + 2) = -0.5, \quad (-2.5 - 2) = -4.5, \quad (-2.5 + 0.4) = -2.1 24=a(0.5)2(4.5)2(2.1)24 = a(-0.5)^2(-4.5)^2(-2.1) 24=a(0.25)(20.25)(2.1)24 = a(0.25)(20.25)(-2.1) 24=a(1.0640625)24 = a(1.0640625) Now solve for aa: a=241.064062522.57a = \frac{24}{1.0640625} \approx 22.57

Step 4: Write the final equation

Now that we know aa, the equation of the polynomial is: f(x)=22.57(x+2)2(x2)2(x+0.4)f(x) = 22.57(x + 2)^2(x - 2)^2(x + 0.4)

Final Answer:

The equation of the degree 5 polynomial in factored form is approximately: f(x)=22.57(x+2)2(x2)2(x+0.4)f(x) = 22.57(x + 2)^2(x - 2)^2(x + 0.4)


Would you like more details on any part of the solution? Or would you like help with a different problem?

Here are 5 related questions to further explore:

  1. How do you determine the multiplicity of a root from a graph?
  2. How do you find the leading term of a polynomial from its factored form?
  3. What is the role of the constant aa in the equation of a polynomial?
  4. How do you graph a degree 5 polynomial given its roots and multiplicities?
  5. How can you use synthetic division to find the equation of a polynomial?

Tip: Always pay attention to how the graph behaves at each root: if it crosses the x-axis, the multiplicity is odd; if it just touches the x-axis, the multiplicity is even!

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Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Roots and Multiplicities
Factored Form of Polynomials
Degree of Polynomials
Graphing Polynomial Functions

Formulas

f(x) = a(x + 2)^2(x - 2)^2(x + 0.4)

Theorems

Fundamental Theorem of Algebra
Multiplicity of Roots

Suitable Grade Level

Grades 11-12