Math Problem Statement

-4 mult. 2, 5/2

Write a polynomial function of least degree with integral coeffiecients that has the given zeros.

Solution

To write a polynomial function of least degree with integer coefficients based on the given zeros, we follow these steps:

Given Zeros:

  • 4-4
  • 22
  • 52\frac{5}{2}

Step 1: Create factors corresponding to the zeros.

Each zero x=rx = r corresponds to a factor of the form (xr)(x - r).

  • For x=4x = -4, the factor is (x+4)(x + 4).
  • For x=2x = 2, the factor is (x2)(x - 2).
  • For x=52x = \frac{5}{2}, the factor is (x52)(x - \frac{5}{2}).

Step 2: Remove any fractions by multiplying the factors.

To ensure integer coefficients, we eliminate the fraction in the third factor. Multiply both sides of (x52)(x - \frac{5}{2}) by 2 to make the coefficient of xx an integer: (x52)=12(2x5).(x - \frac{5}{2}) = \frac{1}{2}(2x - 5). So, we multiply the entire polynomial by 2 later to eliminate the fraction.

Step 3: Multiply the factors.

Now we have the factors: (x+4),(x2),and(2x5).(x + 4), \quad (x - 2), \quad \text{and} \quad (2x - 5). Multiply these factors together to get the polynomial.

First, multiply the first two factors: (x+4)(x2)=x22x+4x8=x2+2x8.(x + 4)(x - 2) = x^2 - 2x + 4x - 8 = x^2 + 2x - 8.

Now multiply this result by (2x5)(2x - 5): (x2+2x8)(2x5).(x^2 + 2x - 8)(2x - 5).

Step 4: Expand the expression:

(x2+2x8)(2x5)=x2(2x5)+2x(2x5)8(2x5).(x^2 + 2x - 8)(2x - 5) = x^2(2x - 5) + 2x(2x - 5) - 8(2x - 5). Now distribute each term: =2x35x2+4x210x16x+40.= 2x^3 - 5x^2 + 4x^2 - 10x - 16x + 40. Combine like terms: =2x3x226x+40.= 2x^3 - x^2 - 26x + 40.

Step 5: Final polynomial function.

The polynomial function of least degree with integer coefficients is: 2x3x226x+40.2x^3 - x^2 - 26x + 40.


Would you like a more detailed explanation of any step or have any questions?


Here are some related questions you might find interesting:

  1. How do you find the degree of a polynomial from its factors?
  2. What are the properties of polynomials with integer coefficients?
  3. Can a polynomial have fractional coefficients even if the zeros are integers?
  4. How would the polynomial change if the zero 52\frac{5}{2} were a rational number with a different denominator?
  5. What’s the relationship between the number of zeros and the degree of a polynomial?

Tip: When working with fractional zeros, always multiply by the denominator to remove fractions and get integer coefficients!

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomial Functions
Factored Form of Polynomials

Formulas

If a polynomial has a root r, then (x - r) is a factor.
Multiplication of polynomial factors to obtain a standard form polynomial.

Theorems

Rational Root Theorem
Fundamental Theorem of Algebra

Suitable Grade Level

Grades 9-12