Math Problem Statement

Write a possible equation for a polynomial whose graph has horizontal intercepts at x = 2, -1/2, -3.

Solution

To write a possible equation for a polynomial whose graph has horizontal intercepts at x=2x = 2, x=12x = -\frac{1}{2}, and x=3x = -3, we construct the equation using the roots. The polynomial equation can be expressed as:

P(x)=a(x2)(x+12)(x+3)P(x) = a(x - 2)\left(x + \frac{1}{2}\right)(x + 3)

Here, aa is a constant that can scale the polynomial but does not change the locations of the intercepts.

Simplify the equation:

  1. Expand x+12x + \frac{1}{2}: x+12=2x+12x + \frac{1}{2} = \frac{2x + 1}{2}

    So the polynomial becomes: P(x)=a(x2)(2x+12)(x+3)P(x) = a(x - 2)\left(\frac{2x + 1}{2}\right)(x + 3)

  2. Simplify by factoring out the denominator: P(x)=a2(x2)(2x+1)(x+3)P(x) = \frac{a}{2}(x - 2)(2x + 1)(x + 3)

  3. Expand the terms if needed. Multiplying (2x+1)(x+3)(2x + 1)(x + 3): (2x+1)(x+3)=2x2+6x+x+3=2x2+7x+3(2x + 1)(x + 3) = 2x^2 + 6x + x + 3 = 2x^2 + 7x + 3

    Now multiply this result by x2x - 2: P(x)=a2(x2)(2x2+7x+3)P(x) = \frac{a}{2}(x - 2)(2x^2 + 7x + 3)

    Expand: P(x)=a2(2x3+7x2+3x4x214x6)P(x) = \frac{a}{2}(2x^3 + 7x^2 + 3x - 4x^2 - 14x - 6)

    Combine like terms: P(x)=a2(2x3+3x211x6)P(x) = \frac{a}{2}(2x^3 + 3x^2 - 11x - 6)

  4. Final simplified polynomial: P(x)=a(x3+32x2112x3)P(x) = a(x^3 + \frac{3}{2}x^2 - \frac{11}{2}x - 3)

A simple example is to let a=2a = 2, making the leading coefficient an integer: P(x)=2(x3+32x2112x3)P(x) = 2(x^3 + \frac{3}{2}x^2 - \frac{11}{2}x - 3)

Do you have any questions or want further clarification?


Related Questions:

  1. What does the coefficient aa represent in the polynomial equation?
  2. How do horizontal intercepts relate to the roots of a polynomial?
  3. Can there be multiple polynomial equations with the same intercepts? If yes, how are they related?
  4. How would you adjust the polynomial if the root x=2x = 2 had a multiplicity of 2?
  5. What is the role of the degree of a polynomial in determining the number of horizontal intercepts?

Tip:

Always verify the intercepts by substituting them back into the equation to ensure the polynomial equals zero at those points.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Roots and Intercepts
Algebra

Formulas

P(x) = a(x - r1)(x - r2)(x - r3)
P(x) = a(x - 2)(x + 1/2)(x + 3)

Theorems

Fundamental Theorem of Algebra

Suitable Grade Level

Grades 10-12