Math Problem Statement

Which values are possible rational roots of 4x^3 + 9x^2 - x + 10 = 0 according to the rational root theorem? Select each correct answer. There are three options: ± 5/2, ± 2, ± 2/3, ± 1/2.

Solution

The given equation is 4x3+9x2x+10=04x^3 + 9x^2 - x + 10 = 0, and the problem asks which values are possible rational roots according to the Rational Root Theorem.

Rational Root Theorem

The theorem states that any rational root of a polynomial equation, given in the form axn+bxn1++k=0ax^n + bx^{n-1} + \cdots + k = 0, must be a fraction pq\frac{p}{q}, where:

  • pp is a factor of the constant term (here, 10).
  • qq is a factor of the leading coefficient (here, 4).

Step 1: Identify the constant and leading coefficients.

  • Constant term k=10k = 10
  • Leading coefficient a=4a = 4

Step 2: List the factors.

  • Factors of 10 (constant term): ±1,±2,±5,±10\pm 1, \pm 2, \pm 5, \pm 10
  • Factors of 4 (leading coefficient): ±1,±2,±4\pm 1, \pm 2, \pm 4

Step 3: List possible rational roots pq\frac{p}{q}.

The possible values of pq\frac{p}{q}, where pp is a factor of 10 and qq is a factor of 4, are: ±1,±12,±14,±2,±5,±52,±10,±102=±5\pm 1, \pm \frac{1}{2}, \pm \frac{1}{4}, \pm 2, \pm 5, \pm \frac{5}{2}, \pm 10, \pm \frac{10}{2} = \pm 5

Thus, the possible rational roots according to the Rational Root Theorem are: ±1,±12,±52,±2,±5\pm 1, \pm \frac{1}{2}, \pm \frac{5}{2}, \pm 2, \pm 5

Step 4: Check the provided answers.

The possible answers are:

  • ±52\pm \frac{5}{2} → Yes, this is valid.
  • ±2\pm 2 → Yes, this is valid.
  • ±23\pm \frac{2}{3} → No, this is not valid.
  • ±12\pm \frac{1}{2} → Yes, this is valid.

Final Answer:

The correct values are:

  • ±52\pm \frac{5}{2}
  • ±2\pm 2
  • ±12\pm \frac{1}{2}

Would you like more details or have any questions?

Here are 5 related questions to further your understanding:

  1. How do you find the factors of a constant term and leading coefficient in the Rational Root Theorem?
  2. Why is the Rational Root Theorem helpful for solving polynomial equations?
  3. How can you check whether a rational root is an actual root of the polynomial?
  4. What happens if none of the rational roots work? What methods could you use next?
  5. How does synthetic division help when testing possible roots?

Tip: Always test the potential rational roots by substituting them into the equation or using synthetic division.

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomials
Rational Root Theorem

Formulas

Rational Root Theorem: possible roots are p/q, where p is a factor of the constant term and q is a factor of the leading coefficient.

Theorems

Rational Root Theorem

Suitable Grade Level

Grades 10-12