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If x = sqrt(3)- sqrt(2) find the value o...

If x = `sqrt(3)- sqrt(2)` find the value of
`x^(3)+ (1)/(x^(3))`

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To find the value of \( x^3 + \frac{1}{x^3} \) where \( x = \sqrt{3} - \sqrt{2} \), we will follow these steps: ### Step 1: Calculate \( x^3 \) Using the formula for the cube of a binomial, we have: \[ x^3 = (\sqrt{3} - \sqrt{2})^3 = (\sqrt{3})^3 - 3(\sqrt{3})^2(\sqrt{2}) + 3(\sqrt{3})(\sqrt{2})^2 - (\sqrt{2})^3 \] Calculating each term: - \( (\sqrt{3})^3 = 3\sqrt{3} \) - \( 3(\sqrt{3})^2(\sqrt{2}) = 3 \cdot 3 \cdot \sqrt{2} = 9\sqrt{2} \) - \( 3(\sqrt{3})(\sqrt{2})^2 = 3\sqrt{3} \cdot 2 = 6\sqrt{3} \) - \( (\sqrt{2})^3 = 2\sqrt{2} \) Putting it all together: \[ x^3 = 3\sqrt{3} - 9\sqrt{2} + 6\sqrt{3} - 2\sqrt{2} \] Combining like terms: \[ x^3 = (3\sqrt{3} + 6\sqrt{3}) + (-9\sqrt{2} - 2\sqrt{2}) = 9\sqrt{3} - 11\sqrt{2} \] ### Step 2: Calculate \( \frac{1}{x} \) To find \( \frac{1}{x} \), we rationalize the denominator: \[ \frac{1}{x} = \frac{1}{\sqrt{3} - \sqrt{2}} \cdot \frac{\sqrt{3} + \sqrt{2}}{\sqrt{3} + \sqrt{2}} = \frac{\sqrt{3} + \sqrt{2}}{(\sqrt{3})^2 - (\sqrt{2})^2} = \frac{\sqrt{3} + \sqrt{2}}{3 - 2} = \sqrt{3} + \sqrt{2} \] ### Step 3: Calculate \( \left( \frac{1}{x} \right)^3 \) Now we need to find \( \left( \sqrt{3} + \sqrt{2} \right)^3 \): \[ \left( \sqrt{3} + \sqrt{2} \right)^3 = (\sqrt{3})^3 + 3(\sqrt{3})^2(\sqrt{2}) + 3(\sqrt{3})(\sqrt{2})^2 + (\sqrt{2})^3 \] Calculating each term: - \( (\sqrt{3})^3 = 3\sqrt{3} \) - \( 3(\sqrt{3})^2(\sqrt{2}) = 9\sqrt{2} \) - \( 3(\sqrt{3})(\sqrt{2})^2 = 6\sqrt{3} \) - \( (\sqrt{2})^3 = 2\sqrt{2} \) Putting it all together: \[ \left( \frac{1}{x} \right)^3 = 3\sqrt{3} + 9\sqrt{2} + 6\sqrt{3} + 2\sqrt{2} \] Combining like terms: \[ \left( \frac{1}{x} \right)^3 = (3\sqrt{3} + 6\sqrt{3}) + (9\sqrt{2} + 2\sqrt{2}) = 9\sqrt{3} + 11\sqrt{2} \] ### Step 4: Calculate \( x^3 + \frac{1}{x^3} \) Now we can find \( x^3 + \frac{1}{x^3} \): \[ x^3 + \frac{1}{x^3} = (9\sqrt{3} - 11\sqrt{2}) + (9\sqrt{3} + 11\sqrt{2}) = 18\sqrt{3} \] ### Final Answer: \[ x^3 + \frac{1}{x^3} = 18\sqrt{3} \]
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