Golden Problem

Algebra Level 3

5 + 2 3 + 5 2 3 = a \sqrt[3]{\sqrt 5 + 2} + \sqrt[3]{\sqrt 5 - 2} = \sqrt{a}

where a a is an integer .Find the value of a a


The answer is 5.

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1 solution

Saurav Pal
Mar 1, 2015

5 + 2 3 + 5 2 3 = a 2 5 + 3 a = a a 20 = ( a 3 ) 2 a a = 5. \sqrt [ 3 ]{ \sqrt { 5 } +2 } +\sqrt [ 3 ]{ \sqrt { 5 } -2 } =\sqrt { a } \\ \Rightarrow \quad 2\sqrt { 5 } +3\sqrt { a } =a\sqrt { a } \\ \Rightarrow \quad 20\quad =\quad { (a-3) }^{ 2 }a\quad \\ \Rightarrow \quad a\quad =\quad 5.\quad \\

any whole square multiplied by an integer should be equal to 20 ......................must be the hint to solve the problem quickly

Uddipan Pal - 5 years, 8 months ago

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