Chapter 10: Problem 76
Simplify each radical. $$ \frac{\sqrt{2}+\sqrt{7}}{\sqrt{5}+\sqrt{3}} $$
Short Answer
Expert verified
\(\frac{\sqrt{10} - \sqrt{6} + \sqrt{35} - \sqrt{21}}{2}\)
Step by step solution
01
- Rationalize the denominator
To simplify the expression \(\frac{\sqrt{2}+\sqrt{7}}{\sqrt{5}+\sqrt{3}}\), first multiply the numerator and the denominator by the conjugate of the denominator. The conjugate of \(\sqrt{5}+\sqrt{3}\) is \(\sqrt{5}-\sqrt{3}\). Thus, multiply by \(\frac{\sqrt{5}-\sqrt{3}}{\sqrt{5}-\sqrt{3}}\).
02
- Apply distribution in the numerator and denominator
Distribute in both the numerator and the denominator: \(\frac{(\sqrt{2} + \sqrt{7})(\sqrt{5} - \sqrt{3})}{(\sqrt{5} + \sqrt{3})(\sqrt{5} - \sqrt{3})}\).
03
- Simplify the denominator using difference of squares
The denominator simplifies using the difference of squares formula: \( (\sqrt{5})^2 - (\sqrt{3})^2 = 5 - 3 = 2 \). So the new denominator is 2.
04
- Expand and simplify the numerator
For the numerator, you need to expand and combine like terms. First, distribute \(\sqrt{2}(\sqrt{5} - \sqrt{3}) = \sqrt{2\cdot5} - \sqrt{2\cdot3} = \sqrt{10} - \sqrt{6}\). Then distribute \(\sqrt{7}(\sqrt{5} - \sqrt{3}) = \sqrt{7\cdot5} - \sqrt{7\cdot3} = \sqrt{35} - \sqrt{21}\). Therefore, the expanded numerator is \(\sqrt{10} - \sqrt{6} + \sqrt{35} - \sqrt{21}\).
05
- Combine the fractions
Putting it all together, the simplified form of the original expression is: \(\frac{\sqrt{10} - \sqrt{6} + \sqrt{35} - \sqrt{21}}{2}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Rationalizing the Denominator
Rationalizing the denominator is a method used to eliminate radicals from the denominator of a fraction. This makes the expression easier to understand and work with.
Here's how it works:
Here's how it works:
- Identify the radical in the denominator.
- Multiply both the numerator and the denominator by the conjugate of the denominator. The conjugate is formed by changing the sign between two terms. For example, the conjugate of \(a + b\) is \(a - b\).
Conjugate Multiplication
Conjugate multiplication is a powerful technique to simplify expressions with radicals. When you multiply a term by its conjugate, you employ the difference of squares formula.
Let's see the steps:
Let's see the steps:
- Take the original expression and the conjugate of the denominator.
- Multiply both the numerator and denominator by the conjugate.
- In the case of \(\frac{\sqrt{2} + \sqrt{7}}{\sqrt{5} + \sqrt{3}}\), we multiply by \(\frac{\sqrt{5} - \sqrt{3}}{\sqrt{5} - \sqrt{3}}\).
Difference of Squares
The difference of squares is a specific algebraic formula used to simplify expressions. It states that \[a^2 - b^2 = (a + b)(a - b)\].
Here's how to apply it:
Using this makes complex radicals easier to manage and understand.
Here's how to apply it:
- Recognize the form \[a^2 - b^2 = (a + b)(a - b)\]
- Use the formula to simplify products of conjugates.
Using this makes complex radicals easier to manage and understand.