Chapter 1: Problem 81
Rationalize Put each fractional expression into standard form by rationalizing the denominator. (a) \(\frac{1}{\sqrt{5 x}}\) (b) \(\sqrt{\frac{x}{5}}\) (c) \(\sqrt[5]{\frac{1}{x^{3}}}\)
Short Answer
Expert verified
(a) \(\frac{\sqrt{5x}}{5x}\); (b) \(\frac{\sqrt{5x}}{5}\); (c) \(\frac{x^{2/5}}{x}\).
Step by step solution
01
Understanding the Problem
We need to rationalize the denominator for each given expression. Rationalizing means removing any radical (such as a square root) from the denominator of a fraction. This involves multiplying both the numerator and the denominator by a term that will eliminate the radical.
02
Rationalizing Part (a)
For the expression \(\frac{1}{\sqrt{5x}}\), we multiply the numerator and the denominator by \(\sqrt{5x}\). This gives us:\[\frac{1}{\sqrt{5x}} \times \frac{\sqrt{5x}}{\sqrt{5x}} = \frac{\sqrt{5x}}{5x}\]Now, the expression is in standard form with a rational denominator.
03
Rationalizing Part (b)
For the expression \(\sqrt{\frac{x}{5}}\), we simplify by recognizing it as \(\frac{\sqrt{x}}{\sqrt{5}}\). We then multiply both the numerator and the denominator by \(\sqrt{5}\):\[\frac{\sqrt{x}}{\sqrt{5}} \times \frac{\sqrt{5}}{\sqrt{5}} = \frac{\sqrt{5x}}{5}\]The resulting expression is in standard form with the denominator rationalized.
04
Rationalizing Part (c)
For \(\sqrt[5]{\frac{1}{x^3}}\), we convert it to \(\frac{1}{x^{3/5}}\) first. We need to make the denominator a rational exponent. Multiply both the numerator and the denominator by \(x^{2/5}\) (since \(3/5 + 2/5 = 1\)): \[\frac{1}{x^{3/5}} \times \frac{x^{2/5}}{x^{2/5}} = \frac{x^{2/5}}{x}\]The expression \(x^{2/5}\) over \(x\) is already rationalized because the denominator is no longer a fraction with a non-integer exponent.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Radicals
Radicals, commonly known as square roots or roots in general, play a significant role in mathematics. The radical symbol (√) is used to denote the root of a number. For instance, \(\sqrt{9}\) equals 3 because 3 multiplied by itself gives 9. Radicals can appear in any part of a mathematical expression, and one common context is within fractions.
Encountering a radical in the denominator of a fraction requires us to rationalize it. This process transforms the expression so that it no longer has a radical in the denominator. Here's why it's essential:
Encountering a radical in the denominator of a fraction requires us to rationalize it. This process transforms the expression so that it no longer has a radical in the denominator. Here's why it's essential:
- Rationalization simplifies algebraic manipulation.
- It is easier to compare fractions without radicals.
- Standard mathematical solutions assume rationalized terms.
Rational Exponents
Rational exponents are another way to represent roots and powers in algebra. Instead of using a radical symbol, we express roots using fractions as exponents. For instance, \(x^{1/2}\) is another way to write \(\sqrt{x}\).
This notation is beneficial because it follows the rules of exponents more naturally. When simplifying algebraic expressions, you'll find operations like multiplication and division more straightforward. Here's a quick overview:
This notation is beneficial because it follows the rules of exponents more naturally. When simplifying algebraic expressions, you'll find operations like multiplication and division more straightforward. Here's a quick overview:
- When raising a power to a power, you multiply the exponents (e.g., \( (x^{1/2})^2 = x^{1/2 \times 2} = x\)).
- Roots as fractions simplify combining different root powers.
- This form can indicate complex roots, such as cube roots or fifth roots (e.g., \( \sqrt[3]{x} = x^{1/3}\)).
Fractions
Fractions express numbers as a ratio of two integers, a form pervasive throughout all of mathematics. They are valuable tools for representing parts of a whole or divisions. Key components of a fraction are the numerator (top part) and the denominator (bottom part).
Simplifying fractions involves ensuring both the numerator and the denominator are reduced to their simplest form. Additionally, a rational denominator – one without radicals or fractions – is preferable because it allows for simpler mathematical operations and comparisons.
Simplifying fractions involves ensuring both the numerator and the denominator are reduced to their simplest form. Additionally, a rational denominator – one without radicals or fractions – is preferable because it allows for simpler mathematical operations and comparisons.
- Fractions can have components that are numbers, variables, or even more complex mathematical expressions.
- Managing fractions often involves operations like finding common denominators, adding, and subtracting.
- When working with fractions in the context of algebra, making sure the denominator is rational is crucial for "clean" results.