document.write( "Question 1209541: x = (16 - 8√5)^(1/3) + (16 + 8√5)^(1/3)
\n" ); document.write( "A = x³ + 12x - 31
\n" ); document.write( "Find A²⁰²⁵
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Algebra.Com's Answer #849389 by greenestamps(13200)\"\" \"About 
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\n" ); document.write( "If \"%2816-8sqrt%285%29%29%5E%281%2F3%29\" and \"%2816%2B8sqrt%285%29%29%5E%281%2F3%29\" are to be simple expressions, then each of them needs to be of the form \"a%2Bb%2Asqrt%285%29\".

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\n" ); document.write( "We need to have \"a%5E3%2B15ab%5E2=16\" and \"3a%5E2b%2B5b%5E3=8\"

\n" ); document.write( "By inspection, these equations are satisfied when a=b=1. So

\n" ); document.write( "\"%2816-8sqrt%285%29%29%5E%281%2F3%29=1-sqrt%285%29\"
\n" ); document.write( "\"%2816%2B8sqrt%285%29%29%5E%281%2F3%29=1%2Bsqrt%285%29\"

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\n" ); document.write( "Then

\n" ); document.write( "\"A=x%5E3%2B12x-31=2%5E3%2B12%282%29-31=8%2B24-31=1\"

\n" ); document.write( "And finally

\n" ); document.write( "\"A%5E2025=1%5E2025=1\"

\n" ); document.write( "ANSWER: 1
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