Math Problem Statement

Analyze the polynomial function f(x) = x^3 - 4x^2 - x + 4. Use the leading coefficient test to determine the end behavior and find the x-intercepts.

Solution

Let's work through the problem you've shared, which involves analyzing the polynomial function f(x)=x34x2x+4f(x) = x^3 - 4x^2 - x + 4.

Part (a) - End Behavior:

You're asked to determine the end behavior of the function using the leading coefficient test. This function has a degree of 3, which is odd, and the leading coefficient of x3x^3 is positive (1). For a cubic function with a positive leading coefficient, the end behavior will be:

  • The graph falls to the left and rises to the right.

This matches the answer marked as A: The graph falls to the left and rises to the right.

Part (b) - X-Intercepts:

To find the x-intercepts, we need to solve f(x)=0f(x) = 0, which gives the roots of the polynomial:

x34x2x+4=0x^3 - 4x^2 - x + 4 = 0

The given x-intercepts are x=1,4,1x = 1, 4, -1, which means these are the points where the graph touches or crosses the x-axis. At each intercept:

  • At x=1x = 1, the graph crosses the x-axis.
  • At x=4x = 4, the graph crosses the x-axis.
  • At x=1x = -1, the graph crosses the x-axis.

Since the polynomial is degree 3, it must cross the x-axis at these points because odd-degree functions always cross the x-axis at least once.

Part (c) - Does the Graph Cross at Specific X-Intercepts?

The question seems to ask whether the graph crosses the x-axis at specific intercepts or simply touches it. Since the graph crosses the x-axis at all three given x-values, the answer to the selection part B ("There are no x-intercepts where the graph does not cross the x-axis") would be false.

Would you like more detailed explanations or to go further into the graphing analysis?


Here are 5 follow-up questions related to this material:

  1. How does the degree of a polynomial affect its end behavior?
  2. What happens to the graph of a cubic function when the leading coefficient is negative?
  3. How can you find whether a function touches or crosses the x-axis at a root?
  4. Can a cubic function have only one x-intercept? Explain why or why not.
  5. What does the sign of the leading term indicate about the direction of the graph?

Tip: When solving polynomial equations, factorization or the Rational Root Theorem can help find x-intercepts.

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Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Graph Analysis
End Behavior

Formulas

End behavior of polynomials
Solving polynomial equations for x-intercepts

Theorems

The Leading Coefficient Test
Rational Root Theorem

Suitable Grade Level

Grades 10-12