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What is the square root of \(\left(8+2\sqrt{15}\right)\) ?

  • A.\(2\sqrt{5} + 2\sqrt{3}\)
  • B.\(\sqrt{5} + \sqrt{3}\)
  • C.\(\sqrt{2} + \sqrt{6}\)
  • D.\(2\sqrt{2} + 2\sqrt{6}\)

Answer: B

\(8+2\sqrt{15}\\= 5+3 + 2 \times\sqrt{5} \times \sqrt{3}\\=(\sqrt{5})^2+(\sqrt{3})^2 + (2 \times\sqrt{5} \times \sqrt{3})\\= (\sqrt{5} +\sqrt{3} )^2\\ \text{Hence, }\sqrt{\left(8+2\sqrt{15}\right)} = \sqrt{(\sqrt{5} +\sqrt{3} )^2} = \sqrt{5} +\sqrt{3}\)

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