document.write( "Question 433406: A = ln(x)-Bx
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Algebra.Com's Answer #300523 by richard1234(7193)\"\" \"About 
You can put this solution on YOUR website!
\"A+=+ln%28x%29+-+ln%28e%5E%28Bx%29%29+=+ln%28x%2F%28e%5E%28Bx%29%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"e%5EA+=+x%2Fe%5E%28Bx%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"e%5EA+=+xe%5E%28-Bx%29\" Multiply both sides by -B\r
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\n" ); document.write( "\n" ); document.write( "\"-Be%5EA+=+-Bxe%5E%28-Bx%29\"\r
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\n" ); document.write( "\n" ); document.write( "There is a certain function called the Lambert W-function defined as the inverse of the function \"f%28z%29+=+ze%5Ez\". Here, we have \"f%28-Bx%29+=+-Bxe%5E%28-Bx%29\" so it follows that if we take the W-function of both sides,\r
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\n" ); document.write( "\n" ); document.write( "\"-Bx+=+W%28-Be%5EA%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-1%2FB%29W%28-Be%5EA%29\"\r
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\n" ); document.write( "\n" ); document.write( "This is pretty much the simplest form that one can express x in, even though the W-function is somewhat obscure. There is, of course, using Newton's method, but it is very unlikely that a real number will be obtained.\r
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\n" ); document.write( "\n" ); document.write( "Also, I checked my answer on Wolfram Alpha by putting arbitrary values for A and B (e.g. A = 253, B = 19), and it came out with the solution \"x+=+%28-1%2F19%29W%28-19e%5E253%29\".\r
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\n" ); document.write( "\n" ); document.write( "http://www.wolframalpha.com/input/?i=253+%3D+ln%28x%29+-+19x\r
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\n" ); document.write( "\n" ); document.write( "Wikipedia article about the W-function:
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