Chapter 5: Problem 70
Rationalize the denominator and simplify. All variables represent positive real numbers. \(\frac{\sqrt{x}}{\sqrt{x}-1}\)
Short Answer
Expert verified
The rationalized and simplified expression is \(\frac{x + \sqrt{x}}{x - 1}\).
Step by step solution
01
Identify the Conjugate of the Denominator
To rationalize the denominator, we need the conjugate of the denominator. If the denominator is \( \sqrt{x} - 1 \), its conjugate is \( \sqrt{x} + 1 \).
02
Multiply Numerator and Denominator by the Conjugate
Multiply both the numerator and the denominator of the fraction by \( \sqrt{x} + 1 \) to get: \[ \frac{\sqrt{x}}{\sqrt{x} - 1} \times \frac{\sqrt{x} + 1}{\sqrt{x} + 1} = \frac{\sqrt{x} (\sqrt{x} + 1)}{(\sqrt{x} - 1)(\sqrt{x} + 1)} \].
03
Simplify the Denominator using Difference of Squares
The denominator \((\sqrt{x} - 1)(\sqrt{x} + 1)\) can be simplified using the difference of squares formula \((a - b)(a + b) = a^2 - b^2\). So, \((\sqrt{x})^2 - 1^2 = x - 1\).
04
Distribute and Simplify the Numerator
Distribute \(\sqrt{x}\) in the numerator: \(\sqrt{x} \cdot \sqrt{x} + \sqrt{x} \cdot 1 = x + \sqrt{x}\).
05
Combine Simplified Numerator and Denominator
Now we can write the simplified expression: \[ \frac{x + \sqrt{x}}{x - 1} \]. This is the expression with a rationalized denominator.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Conjugate
When rationalizing a denominator, the first step often involves identifying the conjugate of the denominator. But, what exactly is a conjugate? In algebra, the conjugate of a binomial expression \(a - b\) is simply \(a + b\). In our exercise, the denominator \(\sqrt{x} - 1\) has the conjugate \(\sqrt{x} + 1\). The trick here is that multiplying a binomial by its conjugate enables the removal of radicals or complex numbers from the denominator.
Why use conjugates, you ask?
Why use conjugates, you ask?
- Conjugates create a "difference of squares" scenario.
- They help simplify expressions by making the denominator a rational number.
Difference of Squares
The concept of difference of squares is not as complicated as it sounds. It is simply an algebraic tool. When a binomial is multiplied by its conjugate, it leads to a difference of squares. The difference of squares formula is a useful math identity given by \(a^2 - b^2\) when \(a = b\).
For instance, multiplying \(\sqrt{x} - 1\) by \(\sqrt{x} + 1\) yields \( (\sqrt{x})^2 - 1^2 = x - 1\). Notice how this multiplication eliminates the radical that originally appeared in the denominator.
Using this formula effectively allows for radical expressions to be simplified, leading to a much more straightforward form.
For instance, multiplying \(\sqrt{x} - 1\) by \(\sqrt{x} + 1\) yields \( (\sqrt{x})^2 - 1^2 = x - 1\). Notice how this multiplication eliminates the radical that originally appeared in the denominator.
Using this formula effectively allows for radical expressions to be simplified, leading to a much more straightforward form.
Simplification
Simplification is a central component of algebra that makes mathematical expressions more manageable. Once you've rationalized the denominator using a conjugate, the next goal is to simplify the resulting expression.
In the context of the exercise, the numerator \(\sqrt{x}(\sqrt{x} + 1)\) simplifies to \(x + \sqrt{x}\). Here, you distribute \(\sqrt{x}\) by applying basic distributive law: multiply \(\sqrt{x}\) by each term in the binomial. Keep track of exponents while ensuring your work remains organized.
In the context of the exercise, the numerator \(\sqrt{x}(\sqrt{x} + 1)\) simplifies to \(x + \sqrt{x}\). Here, you distribute \(\sqrt{x}\) by applying basic distributive law: multiply \(\sqrt{x}\) by each term in the binomial. Keep track of exponents while ensuring your work remains organized.
- Combine like terms if possible.
- Simplify expressions by eliminating unnecessary radicals.
Radicals
Radicals often present themselves as intimidating elements in mathematical expressions, but understanding them can demystify the process of rationalization. A radical usually indicates a root, such as a square root or cube root. In our exercise, \(\sqrt{x}\) appears as the square root, a common form of radicals.
Why are radicals important?
Why are radicals important?
- They help express numbers that are not perfect powers.
- Allow for solving equations that involve roots.