Chapter 10: Problem 15
Add or subtract. \(\frac{\sqrt{20 x}}{9}+\sqrt{\frac{5 x}{9}}\)
Short Answer
Expert verified
The result is \( \frac{5\sqrt{5x}}{9} \).
Step by step solution
01
Simplify Square Roots
Start by simplifying the square roots in each expression. For the first term, \( \sqrt{20x} \) can be written as \( \sqrt{4 \times 5x} \) which simplifies to \( 2\sqrt{5x} \). The second term involves \( \sqrt{\frac{5x}{9}} \), which can be written as \( \sqrt{\frac{5x}{9}} = \frac{\sqrt{5x}}{3} \). This is because \( \sqrt{\frac{5x}{9}} = \sqrt{\frac{1}{9}} \times \sqrt{5x} \) and \( \sqrt{\frac{1}{9}} = \frac{1}{3} \). Thus, the terms become \( \frac{2\sqrt{5x}}{9} \) and \( \frac{\sqrt{5x}}{3} \).
02
Find a Common Denominator
To add these two fractions, we need a common denominator. The two denominators are 9 and 3. The least common denominator is 9. Rewrite \( \frac{\sqrt{5x}}{3} \) with the common denominator 9: \( \frac{\sqrt{5x}}{3} = \frac{\sqrt{5x} \times 3}{3 \times 3} = \frac{3\sqrt{5x}}{9} \).
03
Add Fractions
Now that both fractions have the same denominator, add them: \( \frac{2\sqrt{5x}}{9} + \frac{3\sqrt{5x}}{9} = \frac{(2\sqrt{5x} + 3\sqrt{5x})}{9} = \frac{5\sqrt{5x}}{9} \).
04
Simplify the Expression
The final expression \( \frac{5\sqrt{5x}}{9} \) is already in its simplest form, and no further simplification is possible.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Simplifying Square Roots
Simplifying square roots is a key skill in algebra. The process involves expressing the square root of a number or variable in its simplest form.
- To simplify a square root, find the largest perfect square factor of the number or expression under the square root.
- For example, with the expression \( \sqrt{20x} \), recognize that 20 can be factored into \( 4 \times 5 \), where 4 is a perfect square.
- This allows us to rewrite \( \sqrt{20x} \) as \( \sqrt{4 \times 5x} \), which simplifies further to \( 2\sqrt{5x} \).
- A similar approach applies to fractional square roots, such as \( \sqrt{\frac{5x}{9}} \).
- This can be expressed as \( \frac{\sqrt{5x}}{\sqrt{9}} \), and since \( \sqrt{9} = 3 \), it becomes \( \frac{\sqrt{5x}}{3} \).
Common Denominator
When adding or subtracting fractions, finding a common denominator is important. It ensures that the fractions are compatible for direct addition or subtraction.
- The common denominator is a shared multiple of the denominators of the fractions you are working with.
- For the fractions \( \frac{2\sqrt{5x}}{9} \) and \( \frac{\sqrt{5x}}{3} \), notice the denominators: 9 and 3.
- The least common denominator here is 9, since it is the smallest number that both denominators can divide into without leaving a remainder.
- Adjust the second fraction by expressing \( \frac{\sqrt{5x}}{3} \) as \( \frac{3\sqrt{5x}}{9} \) to match the common denominator found.
Adding Fractions
Once fractions have a common denominator, you can add or subtract their numerators directly.
- Take the fractions \( \frac{2\sqrt{5x}}{9} \) and \( \frac{3\sqrt{5x}}{9} \) which both now have the denominator 9.
- Add the numerators: \( 2\sqrt{5x} + 3\sqrt{5x} = 5\sqrt{5x} \).
- The result is then written over the common denominator: \( \frac{5\sqrt{5x}}{9} \).
- This expression is the sum of the two fractions, simplified and combined.