Math Problem Statement

Sketch a polynomial that has these characteristics: - It has degree 4 - It has roots at -4, -2, and 3 (multiplicity 2) - As x approaches -∞, f(x) approaches -∞ - As x approaches ∞, f(x) approaches -∞

Solution

To sketch a polynomial f(x)f(x) with the given characteristics, let’s analyze each condition:

1. Polynomial Degree

  • The polynomial has a degree of 4, which means the leading term will be x4x^4, making it a quartic polynomial.

2. Roots

  • The polynomial has roots at:
    • x=4x = -4 (multiplicity 1, so it crosses the x-axis at this root).
    • x=2x = -2 (multiplicity 1, so it also crosses the x-axis here).
    • x=3x = 3 (multiplicity 2, so it touches the x-axis and does not cross it at this root).

3. End Behavior

  • As xx \to -\infty, f(x)f(x) \to -\infty.
  • As xx \to \infty, f(x)f(x) \to -\infty.

Since the end behavior of the polynomial shows that f(x)f(x) approaches -\infty on both ends, the leading coefficient must be negative. Thus, the polynomial will have the form: f(x)=a(x+4)(x+2)(x3)2f(x) = -a(x + 4)(x + 2)(x - 3)^2 where a>0a > 0 (to ensure the correct end behavior).

Steps to Sketch

  1. Plot the roots on the x-axis at x=4x = -4, x=2x = -2, and x=3x = 3.
  2. Behavior at each root:
    • At x=4x = -4 and x=2x = -2: the function crosses the x-axis.
    • At x=3x = 3: the function touches the x-axis and turns back, due to the multiplicity of 2.
  3. End Behavior: The graph heads down to -\infty as xx approaches both -\infty and ++\infty.

Would you like a specific graph of this polynomial, or further explanation on any of the steps?


Related Questions:

  1. How does the multiplicity of a root affect the shape of the graph near that root?
  2. Why does a negative leading coefficient in a quartic polynomial result in both ends going to -\infty?
  3. What happens if we change the multiplicity of the root at x=3x = 3 to 1?
  4. How would the graph look if the leading coefficient were positive?
  5. Can a quartic polynomial have end behavior where one end goes to ++\infty and the other to -\infty?

Tip:

When sketching polynomials, always check the end behavior first, as it gives you a good idea of the overall direction of the graph on both sides.

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Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Roots and Multiplicity
End Behavior of Polynomials

Formulas

General form of a polynomial with given roots: f(x) = a(x - r1)(x - r2)...

Theorems

Fundamental Theorem of Algebra

Suitable Grade Level

Grades 10-12