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Mathematics

Simplify : 7+353+573535\dfrac{7 + 3\sqrt{5}}{3 + \sqrt{5}} - \dfrac{7 - 3\sqrt{5}}{3 - \sqrt{5}}

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Answer

Given,

Equation : 7+353+573535\dfrac{7 + 3\sqrt{5}}{3 + \sqrt{5}} - \dfrac{7 - 3\sqrt{5}}{3 - \sqrt{5}}

Simplifying the above equation :

(7+35)×(35)(735)×(3+5)(3+5)×(35)(2175+9515)(21+759515)32(5)22175+95152175+95+15954545\Rightarrow \dfrac{(7 + 3\sqrt{5}) \times (3 - \sqrt{5}) - (7 - 3\sqrt{5}) \times (3 + \sqrt{5})}{(3 + \sqrt{5}) \times (3 - \sqrt{5})} \\[1em] \Rightarrow \dfrac{(21 - 7\sqrt{5} + 9\sqrt{5} - 15)-(21 + 7\sqrt{5} - 9\sqrt{5} - 15)}{3^2 - (\sqrt{5})^2} \\[1em] \Rightarrow \dfrac{21 - 7\sqrt{5} + 9\sqrt{5} - 15 - 21 - 7\sqrt{5} + 9\sqrt{5} + 15}{9 - 5} \\[1em] \Rightarrow \dfrac{4\sqrt{5}}{4} \\[1em] \Rightarrow \sqrt{5}

Hence, 7+353+573535=5\dfrac{7 + 3\sqrt{5}}{3 + \sqrt{5}}- \dfrac{7 - 3\sqrt{5}}{3 - \sqrt{5}} = \sqrt{5}.

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