Multiplying Rational Functions

Oct 13, 2025 by wbrum.org 23 views

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Introduction

In this article, we will explore the process of multiplying rational functions together. Rational functions are a type of algebraic expression that consists of a polynomial divided by another polynomial. Multiplying rational functions involves multiplying the numerators and denominators separately and then simplifying the resulting expression.

What are Rational Functions?

Rational functions are algebraic expressions that consist of a polynomial divided by another polynomial. They are of the form:

f(x) = p(x) / q(x)

where p(x) and q(x) are polynomials. Rational functions can be used to model a wide range of real-world phenomena, such as the motion of objects, the growth of populations, and the behavior of electrical circuits.

Multiplying Rational Functions

To multiply rational functions, we need to multiply the numerators and denominators separately. The numerator of the first rational function is x^2 + 3x - 18, and the denominator is x^2 - 9. The second rational function is x^2 + 7x + 12.

Step 1: Multiply the Numerators

To multiply the numerators, we need to multiply the two polynomials together. We can do this by multiplying each term in the first polynomial by each term in the second polynomial.

(x^2 + 3x - 18) × (x^2 + 7x + 12)

= x^2(x2 + 7x + 12) + 3x(x^2 + 7x + 12) - 18(x^2 + 7x + 12)

= x^4 + 7x^3 + 12x^2 + 3x^3 + 21x^2 + 36x - 18x^2 - 126x - 216

= x^4 + 10x^3 + 15x^2 - 90x - 216

Step 2: Multiply the Denominators

To multiply the denominators, we need to multiply the two polynomials together.

(x^2 - 9) × (x^2 + 7x + 12)

= x^2(x2 + 7x + 12) - 9(x^2 + 7x + 12)

= x^4 + 7x^3 + 12x^2 - 9x^2 - 63x - 108

= x^4 - 2x^2 - 63x - 108

Step 3: Simplify the Expression

Now that we have multiplied the numerators and denominators, we can simplify the expression by dividing the numerator by the denominator.

(x^4 + 10x^3 + 15x^2 - 90x - 216) / (x^4 - 2x^2 - 63x - 108)

To simplify this expression, we need to factor the numerator and denominator.

Factoring the Numerator

The numerator can be factored as follows:

x^4 + 10x^3 + 15x^2 - 90x - 216

= (x^2 + 6x + 12)(x^2 + 4x + 18)

Factoring the Denominator

The denominator can be factored as follows:

x^4 - 2x^2 - 63x - 108

= (x^2 - 9)(x^2 + 7x + 12)

Simplifying the Expression

Now that we have factored the numerator and denominator, we can simplify the expression by canceling out any common factors.

(x^2 + 6x + 12)(x^2 + 4x + 18) / ((x^2 - 9)(x^2 + 7x + 12))

= (x^2 + 6x + 12)(x^2 + 4x + 18) / (x^2 - 9)(x^2 + 7x + 12)

= (x^2 + 6x + 12)(x^2 + 4x + 18) / (x^2 - 9

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Introduction

In our previous article, we explored the process of multiplying rational functions together. Rational functions are a type of algebraic expression that consists of a polynomial divided by another polynomial. Multiplying rational functions involves multiplying the numerators and denominators separately and then simplifying the resulting expression.

Q&A

Q: What is the first step in multiplying rational functions?

A: The first step in multiplying rational functions is to multiply the numerators and denominators separately.

Q: How do I multiply the numerators?

A: To multiply the numerators, you need to multiply the two polynomials together. You can do this by multiplying each term in the first polynomial by each term in the second polynomial.

Q: How do I multiply the denominators?

A: To multiply the denominators, you need to multiply the two polynomials together.

Q: What is the next step after multiplying the numerators and denominators?

A: The next step is to simplify the expression by dividing the numerator by the denominator.

Q: How do I simplify the expression?

A: To simplify the expression, you need to factor the numerator and denominator and then cancel out any common factors.

Q: What is factoring?

A: Factoring is the process of expressing a polynomial as a product of simpler polynomials.

Q: Why do I need to factor the numerator and denominator?

A: You need to factor the numerator and denominator to simplify the expression and cancel out any common factors.

Q: What is a common factor?

A: A common factor is a factor that appears in both the numerator and denominator.

Q: How do I cancel out common factors?

A: To cancel out common factors, you need to divide the numerator and denominator by the common factor.

Q: What is the final step in multiplying rational functions?

A: The final step is to write the simplified expression in the form of a rational function.

Q: What is a rational function?

A: A rational function is an algebraic expression that consists of a polynomial divided by another polynomial.

Q: Why is it important to multiply rational functions?

A: It is important to multiply rational functions because it allows you to simplify complex expressions and solve problems in algebra and calculus.

Q: Can you give an example of multiplying rational functions?

A: Yes, let's consider the following example:

(x^2 + 3x - 18) / (x^2 - 9) × (x^2 + 7x + 12)

To multiply these rational functions, we need to multiply the numerators and denominators separately and then simplify the resulting expression.

Q: How do I multiply the numerators in this example?

A: To multiply the numerators, we need to multiply the two polynomials together.

(x^2 + 3x - 18) × (x^2 + 7x + 12)

= x^4 + 7x^3 + 12x^2 + 3x^3 + 21x^2 + 36x - 18x^2 - 126x - 216

= x^4 + 10x^3 + 15x^2 - 90x - 216

Q: How do I multiply the denominators in this example?

A: To multiply the denominators, we need to multiply the two polynomials together.

(x^2 - 9) × (x^2 + 7x + 12)

= x^4 + 7x^3 + 12x^2 - 9x^2 - 63x - 108

= x^4 - 2x^2 - 63x - 108

Q: What is the next step after multiplying the numerators and denominators in this example?

A: The next step is to simplify the expression by dividing the numerator by the denominator.

(x^4 + 10x^3 + 15x^2 - 90x - 216) / (x^4 - 2x^2 - 63x - 108)

To simplify this expression, we need to factor the numerator and denominator and then cancel out any common factors.

Q: How do I factor the numerator in this example?

A: The numerator can be factored as follows:

x^4 + 10x^3 + 15x^2 - 90x - 216

= (x^2 + 6x + 12)(x^2 + 4x + 18)

Q: How do I factor the denominator in this example?

A: The denominator can be factored as follows:

x^4 - 2x^2 - 63x - 108

= (x^2 - 9)(x^2 + 7x + 12)

Q: What is the final step in multiplying rational functions in this example?

A: The final step is to write the simplified expression in the form of a rational function.

(x^2 + 6x + 12)(x^2 + 4x + 18) / ((x^2 - 9)(x^2 + 7x + 12))

= (x^2 + 6x + 12)(x^2 + 4x + 18) / (x^2 - 9)(x^2 + 7x + 12)

This is the final answer to the problem.

Conclusion

Multiplying rational functions is an important skill in algebra and calculus. It allows you to simplify complex expressions and solve problems. In this article, we explored the process of multiplying rational functions together and provided a step-by-step guide on how to do it. We also answered some common questions about multiplying rational functions.