document.write( "Question 1204647: Suppose \"+43%5E%283log+%2813%2C56%29%29+=+56%5E%28x%2Alog+%2811%2C43%29%29+\", where \"x+=+log+%28b%2Cn%29\". Compute the pair of positive integers (b,n) that satisfies this equation, where b is the minimum value greater than 10 \n" ); document.write( "
Algebra.Com's Answer #841044 by ikleyn(52909)\"\" \"About 
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\n" ); document.write( "Suppose \"+43%5E%283log+%2813%2C56%29%29+=+56%5E%28x%2Alog+%2811%2C43%29%29+\", where \"x+=+log+%28b%2Cn%29\".
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document.write( "The starting equation is  \"43%5E%283log%2813%2C56%29%29\" = \"56%5E%28x%2Alog+%2811%2C43%29%29\".    (1)\r\n" );
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document.write( "Take log base 11 of both sides.  \r\n" );
document.write( "Using basic elementary properties of logarithms, you will get\r\n" );
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document.write( "    \"3%2Alog%2813%2C56%29%2Alog%2811%2C43%29\" = \"x%2Alog%2811%2C43%29%2Alog%2811%2C56%29\".    (2)\r\n" );
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document.write( "Cancel common factor  \"log%2811%2C43%29\"  in both sides.  You will get\r\n" );
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document.write( "    \"3%2Alog%2813%2C56%29%29\" = \"x%2Alog%2811%2C56%29\".    (3)\r\n" );
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document.write( "Using  \"log%28a%2Cb%29\" = \"1%2Flog%28b%2Ca%29\", rewrite equation (3) in equivalent form\r\n" );
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document.write( "    \"3%2Flog%2856%2C13%29\" = \"x%2Flog%2856%2C11%29\".     (4)\r\n" );
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document.write( "At this point, you have logarithms with common (the same) base 56.\r\n" );
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document.write( "Rewrite proportion (4) in equivalent form\r\n" );
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document.write( "    \"3%2Fx\" = \"log%2856%2C13%29%2Flog%2856%2C11%29\".    (5)\r\n" );
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document.write( "According to the \"base change\" formula for logarithms, the right side of (5) is\r\n" );
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document.write( "    \"log%2856%2C13%29%2Flog%2856%2C11%29\" = \"log%2811%2C13%29\".    (6)\r\n" );
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document.write( "So, proportion (5) is now this significantly simplified equation\r\n" );
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document.write( "    \"3%2Fx\" = \"log%2811%2C13%29\".    (7)\r\n" );
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document.write( "Rewrite it equivalently in this form\r\n" );
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document.write( "    x = \"3%2Flog%2811%2C13%29\".\r\n" );
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document.write( "Again, apply the formula  \"1%2Flog%2811%2C13%29\" = \"log%2813%2C11%29\" to get\r\n" );
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document.write( "    x = \"3%2Alog%2813%2C11%29\".\r\n" );
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document.write( "But they want x = \"log+%28b%2Cn%29\"   (see the description of the problem).\r\n" );
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document.write( "It leads us to this equation\r\n" );
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document.write( "    \"log+%28b%2Cn%29\" = \"3%2Alog%2813%2C11%29\",\r\n" );
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document.write( "which is the same as\r\n" );
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document.write( "    \"log+%28b%2Cn%29\" = \"log%2813%2C11%5E3%29\".    (8)\r\n" );
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document.write( "From (8), we get the answer to the problem:  b = 13;  n = \"11%5E3\" = 1331.\r\n" );
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document.write( "ANSWER.  The solution to the problem is  b = 13;  n = \"11%5E3\" = 1331.\r\n" );
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\n" ); document.write( "\n" ); document.write( "In students' jargon,  this problem is a coffin,  that is,  solving it seems impossible.\r
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\n" ); document.write( "\n" ); document.write( "Do not forget to post your  \" THANKS \"  to me for my teaching.\r
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\n" ); document.write( "\n" ); document.write( "When you will post your  \" THANKS \",  please refer to the  ID  number
\n" ); document.write( "of this problem,  which is  1204647.\r
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