The Rational Roots Theorem

Oct 13, 2025 by wbrum.org 102 views

Introduction

In mathematics, polynomial functions are a fundamental concept in algebra and are used to model various real-world phenomena. A polynomial function is an expression consisting of variables and coefficients combined using only addition, subtraction, and multiplication. The rational roots theorem is a powerful tool used to find the roots of a polynomial function, which is a value of the variable that makes the function equal to zero. In this article, we will explore the polynomial function $f(x) = 10x^6 + 7x - 7$ and use the rational roots theorem to determine a possible root at point $P$ .

The Rational Roots Theorem

The rational roots theorem states that if a polynomial function $f(x)$ has integer coefficients, then any rational root of $f(x)$ must be of the form $\frac{p}{q}$ , where $p$ is a factor of the constant term and $q$ is a factor of the leading coefficient. In other words, the rational roots of a polynomial function are all the possible combinations of factors of the constant term and the leading coefficient.

The Polynomial Function $f(x) = 10x^6 + 7x - 7$

The given polynomial function is $f(x) = 10x^6 + 7x - 7$ . To find the possible roots of this function using the rational roots theorem, we need to identify the factors of the constant term and the leading coefficient.

The constant term is $-7$ , which has factors of $\pm 1$ and $\pm 7$ .
The leading coefficient is $10$ , which has factors of $\pm 1$ , $\pm 2$ , $\pm 5$ , and $\pm 10$ .

Possible Rational Roots

Using the rational roots theorem, we can list all the possible rational roots of the polynomial function $f(x) = 10x^6 + 7x - 7$ . These possible roots are all the combinations of factors of the constant term and the leading coefficient.

$\pm 1$
$\pm 7$
$\pm \frac{1}{2}$
$\pm \frac{1}{5}$
$\pm \frac{1}{10}$
$\pm \frac{7}{2}$
$\pm \frac{7}{5}$
$\pm \frac{7}{10}$

The Root at Point $P$

The root at point $P$ may be $\frac{5}{7}$ . To verify this, we can substitute $\frac{5}{7}$ into the polynomial function $f(x) = 10x^6 + 7x - 7$ and check if the result is equal to zero.

$f(\frac{5}{7}) = 10(\frac{5}{7})^6 + 7(\frac{5}{7}) - 7$

$f(\frac{5}{7}) = 10(\frac{15625}{117649}) + \frac{35}{7} - 7$

$f(\frac{5}{7}) = \frac{156250}{117649} + \frac{35}{7} - 7$

$f(\frac{5}{7}) = \frac{156250}{117649} + \frac{245}{49} - \frac{343}{49}$

$f(\frac{5}{7}) = \frac{156250}{117649} - \frac{98}{49}$

$f(\frac{5}{7}) = \frac{156250}{117649} - \frac{392}{49}$

$f(\frac{5}{7}) = \frac{156250}{117649} - \frac{392 \times 2401}{49 \times 2401}$

$f(\frac{5}{7}) = \frac{156250}{117649} - \frac{940492}{117649}$

$f(\frac{5}{7}) = \frac{156250 - 940492}{117649}$

$f(\frac{5}{7}) = \frac{-784242}{117649}$

$f(\frac{5}{7}) = -\frac{784242}{117649}$

Since $f(\frac{5}{7})$ is not equal to zero, the root at point $P$ is not $\frac{5}{7}$ .

Conclusion

In conclusion, the rational roots theorem is a powerful tool used to find the roots of a polynomial function. By identifying the factors of the constant term and the leading coefficient, we can list all the possible rational roots of the polynomial function. However, not all possible roots may be actual roots of the function. In this article, we used the rational roots theorem to determine a possible root at point $P$ for the polynomial function $f(x) = 10x^6 + 7x - 7$ . We found that the root at point $P$ may be $\frac{5}{7}$ , but this was not verified to be an actual root of the function.

Future Work

In the future, we can use the rational roots theorem to find the roots of other polynomial functions. We can also explore other methods for finding the roots of polynomial functions, such as the quadratic formula and synthetic division. Additionally, we can use the rational roots theorem to solve systems of equations and find the solutions to polynomial equations.

References

[1] "Rational Roots Theorem." Math Open Reference, mathopenref.com/rational_roots_theorem.html.
[2] "Polynomial Functions." Math Is Fun, mathisfun.com/algebra/polynomial-functions.html.
[3] "Roots of a Polynomial Function." Wolfram MathWorld, mathworld.wolfram.com/RootsOfAPolynomialFunction.html.

Glossary

Polynomial function: An expression consisting of variables and coefficients combined using only addition, subtraction, and multiplication.
Rational roots theorem: A theorem that states that if a polynomial function has integer coefficients, then any rational root of the function must be of the form $\frac{p}{q}$ , where $p$ is a factor of the constant term and $q$ is a factor of the leading coefficient.
Root of a polynomial function: A value of the variable that makes the function equal to zero.
Leading coefficient: The coefficient of the highest degree term in a polynomial function.
Constant term: The term that does not contain the variable in a polynomial function.
The Polynomial Function and Rational Roots Theorem: Q&A =====================================================

Introduction

In our previous article, we explored the polynomial function $f(x) = 10x^6 + 7x - 7$ and used the rational roots theorem to determine a possible root at point $P$ . In this article, we will answer some frequently asked questions about the polynomial function and the rational roots theorem.

Q: What is the rational roots theorem?

A: The rational roots theorem is a theorem that states that if a polynomial function has integer coefficients, then any rational root of the function must be of the form $\frac{p}{q}$ , where $p$ is a factor of the constant term and $q$ is a factor of the leading coefficient.

Q: How do I find the possible rational roots of a polynomial function?

A: To find the possible rational roots of a polynomial function, you need to identify the factors of the constant term and the leading coefficient. Then, you can list all the possible combinations of these factors to find the possible rational roots.

Q: What is the difference between a possible root and an actual root?

A: A possible root is a value of the variable that makes the function equal to zero, but it may not be an actual root. An actual root is a value of the variable that makes the function equal to zero and is a solution to the equation.

Q: How do I verify if a possible root is an actual root?

A: To verify if a possible root is an actual root, you need to substitute the value into the polynomial function and check if the result is equal to zero.

Q: Can I use the rational roots theorem to find the roots of a polynomial function with non-integer coefficients?

A: No, the rational roots theorem only applies to polynomial functions with integer coefficients. If the coefficients are not integers, you may need to use other methods to find the roots of the function.

Q: Can I use the rational roots theorem to solve systems of equations?

A: Yes, you can use the rational roots theorem to solve systems of equations. By finding the possible rational roots of each equation, you can determine the possible solutions to the system of equations.

Q: What are some common mistakes to avoid when using the rational roots theorem?

A: Some common mistakes to avoid when using the rational roots theorem include:

Not identifying the factors of the constant term and the leading coefficient correctly.
Not listing all the possible combinations of the factors.
Not verifying if a possible root is an actual root.
Not using the correct method to find the roots of the polynomial function.

Q: What are some real-world applications of the rational roots theorem?

A: The rational roots theorem has many real-world applications, including:

Finding the roots of polynomial equations that model real-world phenomena, such as population growth and chemical reactions.
Solving systems of equations that model real-world situations, such as economics and physics.
Finding the solutions to polynomial equations that are used in computer science and engineering.

Conclusion

In conclusion, the rational roots theorem is a powerful tool used to find the roots of polynomial functions. By understanding the theorem and its applications, you can solve a wide range of problems in mathematics and real-world situations. Remember to avoid common mistakes and use the correct method to find the roots of the polynomial function.

Glossary

Polynomial function: An expression consisting of variables and coefficients combined using only addition, subtraction, and multiplication.
Rational roots theorem: A theorem that states that if a polynomial function has integer coefficients, then any rational root of the function must be of the form $\frac{p}{q}$ , where $p$ is a factor of the constant term and $q$ is a factor of the leading coefficient.
Root of a polynomial function: A value of the variable that makes the function equal to zero.
Leading coefficient: The coefficient of the highest degree term in a polynomial function.
Constant term: The term that does not contain the variable in a polynomial function.

References

[1] "Rational Roots Theorem." Math Open Reference, mathopenref.com/rational_roots_theorem.html.
[2] "Polynomial Functions." Math Is Fun, mathisfun.com/algebra/polynomial-functions.html.
[3] "Roots of a Polynomial Function." Wolfram MathWorld, mathworld.wolfram.com/RootsOfAPolynomialFunction.html.

Frequently Asked Questions

Q: What is the rational roots theorem?
A: The rational roots theorem is a theorem that states that if a polynomial function has integer coefficients, then any rational root of the function must be of the form $\frac{p}{q}$ , where $p$ is a factor of the constant term and $q$ is a factor of the leading coefficient.
Q: How do I find the possible rational roots of a polynomial function?
A: To find the possible rational roots of a polynomial function, you need to identify the factors of the constant term and the leading coefficient. Then, you can list all the possible combinations of these factors to find the possible rational roots.
Q: What is the difference between a possible root and an actual root?
A: A possible root is a value of the variable that makes the function equal to zero, but it may not be an actual root. An actual root is a value of the variable that makes the function equal to zero and is a solution to the equation.