Multiply the fraction by the conjugate

Oct 13, 2025 by wbrum.org 89 views

$Multiply the fraction by the conjugate$

Introduction

Rationalizing the denominator is a crucial step in algebraic manipulation, especially when dealing with fractions that have complex or irrational denominators. In this article, we will explore the concept of rationalizing the denominator and provide a step-by-step guide on how to do it.

What is Rationalizing the Denominator?

Rationalizing the denominator involves removing any radical or irrational expressions from the denominator of a fraction. This is done by multiplying the fraction by a cleverly chosen form of 1, which allows us to eliminate the radical or irrational expression from the denominator.

The Conjugate Method

To rationalize a denominator that has more than one term, you multiply the fraction by $\frac{B}{B}$ , where $B$ is the conjugate of the denominator. The conjugate of a binomial expression $a + b$ is $a - b$ . For example, the conjugate of $x + \sqrt{2}$ is $x - \sqrt{2}$ .

Why Does the Conjugate Method Work?

The conjugate method works because when we multiply a binomial expression by its conjugate, the result is a difference of squares. For example, $(x + \sqrt{2})(x - \sqrt{2}) = x^2 - (\sqrt{2})^2 = x^2 - 2$ . This means that the radical or irrational expression is eliminated from the denominator.

Step-by-Step Guide to Rationalizing the Denominator

Here is a step-by-step guide to rationalizing the denominator:

Identify the conjugate: Identify the conjugate of the denominator. If the denominator is a binomial expression $a + b$ , the conjugate is $a - b$ .
Multiply the fraction by the conjugate: Multiply the fraction by $\frac{B}{B}$ , where $B$ is the conjugate of the denominator.
Simplify the expression: Simplify the expression by multiplying out the numerator and denominator.
Eliminate the radical or irrational expression: Eliminate the radical or irrational expression from the denominator.

Example 1: Rationalizing a Denominator with a Binomial Expression

Suppose we want to rationalize the denominator of the fraction $\frac{1}{x + \sqrt{2}}$ . To do this, we multiply the fraction by $\frac{x - \sqrt{2}}{x - \sqrt{2}}$ .

$\frac{1}{x + \sqrt{2}} \cdot \frac{x - \sqrt{2}}{x - \sqrt{2}} = \frac{x - \sqrt{2}}{(x + \sqrt{2})(x - \sqrt{2})}$

Simplifying the expression, we get:

$\frac{x - \sqrt{2}}{x^2 - (\sqrt{2})^2} = \frac{x - \sqrt{2}}{x^2 - 2}$

Example 2: Rationalizing a Denominator with a Trinomial Expression

Suppose we want to rationalize the denominator of the fraction $\frac{1}{x + \sqrt{2} + 3}$ . To do this, we multiply the fraction by $\frac{x - \sqrt{2} - 3}{x - \sqrt{2} - 3}$ .

$\frac{1}{x + \sqrt{2} + 3} \cdot \frac{x - \sqrt{2} - 3}{x - \sqrt{2} - 3} = \frac{x - \sqrt{2} - 3}{(x + \sqrt{2} + 3)(x - \sqrt{2} - 3)}$

Simplifying the expression, we get:

$\frac{x - \sqrt{2} - 3}{x^2 - (\sqrt{2})^2 - 3(x + \sqrt{2}) - 3(x - \sqrt{2})} = \frac{x - \sqrt{2} - 3}{x^2 - 2 - 3x - 3\sqrt{2} + 3x - 3\sqrt{2}} = \frac{x - \sqrt{2} - 3}{x^2 - 2 - 6\sqrt{2}}$

Conclusion

Rationalizing the denominator is an essential step in algebraic manipulation, especially when dealing with fractions that have complex or irrational denominators. By using the conjugate method, we can eliminate the radical or irrational expression from the denominator and simplify the expression. In this article, we provided a step-by-step guide on how to rationalize the denominator and provided two examples to illustrate the concept.

Final Answer

$To rationalize a denominator that has more than one term, you multiply the fraction by $\frac{B}{B}$, where $B$ is the conjugate of the denominator. **This statement is TRUE**.<br/> **Rationalizing the Denominator: A Q&A Guide**$

Introduction

In our previous article, we explored the concept of rationalizing the denominator and provided a step-by-step guide on how to do it. In this article, we will answer some frequently asked questions about rationalizing the denominator.

Q: What is the conjugate of a binomial expression?

A: The conjugate of a binomial expression $a + b$ is $a - b$ . For example, the conjugate of $x + \sqrt{2}$ is $x - \sqrt{2}$ .

Q: Why do we multiply the fraction by the conjugate?

A: We multiply the fraction by the conjugate to eliminate the radical or irrational expression from the denominator. When we multiply a binomial expression by its conjugate, the result is a difference of squares, which eliminates the radical or irrational expression.

Q: How do I identify the conjugate of a binomial expression?

A: To identify the conjugate of a binomial expression, simply change the sign of the second term. For example, the conjugate of $x + \sqrt{2}$ is $x - \sqrt{2}$ .

Q: Can I rationalize the denominator of a fraction with a trinomial expression?

A: Yes, you can rationalize the denominator of a fraction with a trinomial expression. To do this, multiply the fraction by the conjugate of the trinomial expression.

Q: What is the conjugate of a trinomial expression?

A: The conjugate of a trinomial expression $a + b + c$ is $a - b - c$ . For example, the conjugate of $x + \sqrt{2} + 3$ is $x - \sqrt{2} - 3$ .

Q: How do I simplify the expression after multiplying by the conjugate?

A: To simplify the expression after multiplying by the conjugate, multiply out the numerator and denominator and simplify the resulting expression.

Q: Can I rationalize the denominator of a fraction with a rational expression?

A: Yes, you can rationalize the denominator of a fraction with a rational expression. To do this, multiply the fraction by the conjugate of the rational expression.

Q: What is the conjugate of a rational expression?

A: The conjugate of a rational expression $\frac{a}{b}$ is $\frac{a}{-b}$ . For example, the conjugate of $\frac{x}{y}$ is $\frac{x}{-y}$ .

Q: How do I rationalize the denominator of a fraction with a complex expression?

A: To rationalize the denominator of a fraction with a complex expression, multiply the fraction by the conjugate of the complex expression.

Q: What is the conjugate of a complex expression?

A: The conjugate of a complex expression $a + bi$ is $a - bi$ . For example, the conjugate of $x + yi$ is $x - yi$ .

Conclusion

Rationalizing the denominator is an essential step in algebraic manipulation, especially when dealing with fractions that have complex or irrational denominators. By understanding the conjugate method and how to apply it, you can simplify expressions and solve problems with ease. In this article, we answered some frequently asked questions about rationalizing the denominator and provided examples to illustrate the concept.

Final Answer

Rationalizing the denominator is a powerful tool in algebraic manipulation. By understanding the conjugate method and how to apply it, you can simplify expressions and solve problems with ease.