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Find the square root of (i) (2+sqrt(3)...

Find the square root of
`(i) (2+sqrt(3))/(2)`, `(ii) 12-sqrt(68+48sqrt((2)))`.

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To find the square roots of the given expressions, we will solve each part step by step. ### Part (i): Find the square root of \((2 + \sqrt{3})/2\) 1. **Rewrite the Expression**: \[ \sqrt{\frac{2 + \sqrt{3}}{2}} = \frac{\sqrt{2 + \sqrt{3}}}{\sqrt{2}} \] 2. **Simplify the Numerator**: We need to express \(2 + \sqrt{3}\) in a form that allows us to take the square root easily. We can try to express it as a square of a binomial: \[ 2 + \sqrt{3} = \left(\sqrt{a} + \sqrt{b}\right)^2 \] Expanding this gives: \[ a + b + 2\sqrt{ab} = 2 + \sqrt{3} \] By comparing coefficients, we can set: - \(a + b = 2\) - \(2\sqrt{ab} = \sqrt{3}\) From \(2\sqrt{ab} = \sqrt{3}\), we find: \[ \sqrt{ab} = \frac{\sqrt{3}}{2} \implies ab = \frac{3}{4} \] 3. **Solve the System of Equations**: We have the equations: - \(a + b = 2\) - \(ab = \frac{3}{4}\) Let \(a\) and \(b\) be the roots of the quadratic equation: \[ x^2 - (a+b)x + ab = 0 \implies x^2 - 2x + \frac{3}{4} = 0 \] The discriminant is: \[ D = 2^2 - 4 \cdot 1 \cdot \frac{3}{4} = 4 - 3 = 1 \] The roots are: \[ x = \frac{2 \pm 1}{2} \implies x = \frac{3}{2} \text{ or } x = \frac{1}{2} \] Thus, \(a = \frac{3}{2}\) and \(b = \frac{1}{2}\). 4. **Substituting Back**: Now we can write: \[ 2 + \sqrt{3} = \left(\sqrt{\frac{3}{2}} + \sqrt{\frac{1}{2}}\right)^2 \] Therefore: \[ \sqrt{2 + \sqrt{3}} = \sqrt{\frac{3}{2}} + \sqrt{\frac{1}{2}} = \frac{\sqrt{3}}{\sqrt{2}} + \frac{1}{\sqrt{2}} = \frac{\sqrt{3} + 1}{\sqrt{2}} \] 5. **Final Result**: Now substituting back into our expression: \[ \sqrt{\frac{2 + \sqrt{3}}{2}} = \frac{\frac{\sqrt{3} + 1}{\sqrt{2}}}{\sqrt{2}} = \frac{\sqrt{3} + 1}{2} \] ### Part (ii): Find the square root of \(12 - \sqrt{68 + 48\sqrt{2}}\) 1. **Rewrite the Expression**: First, we simplify the expression under the square root: \[ \sqrt{68 + 48\sqrt{2}} \] 2. **Express as a Square**: We want to express \(68 + 48\sqrt{2}\) as \((a + b\sqrt{2})^2\): \[ (a + b\sqrt{2})^2 = a^2 + 2ab\sqrt{2} + 2b^2 \] Comparing coefficients, we have: - \(a^2 + 2b^2 = 68\) - \(2ab = 48\) From \(2ab = 48\), we find: \[ ab = 24 \] 3. **Solve the System of Equations**: We have: - \(a^2 + 2b^2 = 68\) - \(ab = 24\) Substitute \(b = \frac{24}{a}\) into the first equation: \[ a^2 + 2\left(\frac{24}{a}\right)^2 = 68 \] Simplifying gives: \[ a^2 + \frac{1152}{a^2} = 68 \] Multiplying through by \(a^2\) leads to: \[ a^4 - 68a^2 + 1152 = 0 \] Let \(x = a^2\): \[ x^2 - 68x + 1152 = 0 \] Using the quadratic formula: \[ x = \frac{68 \pm \sqrt{68^2 - 4 \cdot 1152}}{2} \] Calculate the discriminant: \[ 68^2 - 4608 = 4624 \implies \sqrt{4624} = 68 \] Thus: \[ x = \frac{68 \pm 68}{2} \implies x = 68 \text{ or } 0 \] Therefore, \(a^2 = 68\) and \(b^2 = 0\). 4. **Finding \(a\) and \(b\)**: Since \(b = 0\), we have: \[ a = 8 \] Thus: \[ \sqrt{68 + 48\sqrt{2}} = 8 + 0\sqrt{2} = 8 \] 5. **Final Result**: Now substituting back into our expression: \[ 12 - \sqrt{68 + 48\sqrt{2}} = 12 - 8 = 4 \] Therefore: \[ \sqrt{4} = 2 \] ### Final Answers: 1. \(\sqrt{\frac{2 + \sqrt{3}}{2}} = \frac{\sqrt{3} + 1}{2}\) 2. \(\sqrt{12 - \sqrt{68 + 48\sqrt{2}}} = 2\)
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ML KHANNA-LOGARITHMS AND SURDS-Problem Set (4)
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