Question
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Rationalize the denominator and simplify. \[ \frac{\sqrt{7}}{14-\sqrt{7}} \]

Ask by Lyons Newton. in the United States
Jan 23,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

\[ \frac{2\sqrt{7} + 1}{27} \]

Solution

To rationalize the denominator and simplify the expression: \[ \frac{\sqrt{7}}{14 - \sqrt{7}} \] **Step 1: Multiply by the Conjugate** Multiply the numerator and the denominator by the conjugate of the denominator, which is \(14 + \sqrt{7}\): \[ \frac{\sqrt{7}}{14 - \sqrt{7}} \times \frac{14 + \sqrt{7}}{14 + \sqrt{7}} = \frac{\sqrt{7}(14 + \sqrt{7})}{(14 - \sqrt{7})(14 + \sqrt{7})} \] **Step 2: Simplify the Denominator** Use the difference of squares formula \( (a - b)(a + b) = a^2 - b^2 \): \[ (14 - \sqrt{7})(14 + \sqrt{7}) = 14^2 - (\sqrt{7})^2 = 196 - 7 = 189 \] **Step 3: Expand the Numerator** \[ \sqrt{7}(14 + \sqrt{7}) = 14\sqrt{7} + 7 \] **Step 4: Combine and Simplify** \[ \frac{14\sqrt{7} + 7}{189} = \frac{7(2\sqrt{7} + 1)}{7 \times 27} = \frac{2\sqrt{7} + 1}{27} \] **Final Answer:** \[ \frac{2\sqrt{7} + 1}{27} \]

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Mind Expander

To rationalize the denominator of \(\frac{\sqrt{7}}{14-\sqrt{7}}\), we multiply the numerator and the denominator by the conjugate of the denominator, which is \(14+\sqrt{7}\): \[ \frac{\sqrt{7}}{14-\sqrt{7}} \cdot \frac{14+\sqrt{7}}{14+\sqrt{7}} = \frac{\sqrt{7}(14+\sqrt{7})}{(14-\sqrt{7})(14+\sqrt{7})} \] The denominator simplifies using the difference of squares: \[ (14 - \sqrt{7})(14 + \sqrt{7}) = 14^2 - (\sqrt{7})^2 = 196 - 7 = 189 \] Now simplifying the numerator: \[ \sqrt{7}(14+\sqrt{7}) = 14\sqrt{7} + 7 \] Putting it all together, we have: \[ \frac{14\sqrt{7} + 7}{189} \] Now we can simplify the fraction: \[ \frac{7 + 14\sqrt{7}}{189} = \frac{1}{27} + \frac{14\sqrt{7}}{189} \] Thus, the final simplified expression is: \[ \frac{14\sqrt{7} + 7}{189} \]

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