document.write( "Question 1157536: Prove that : If int(1/(xf(x)) dx = f(f(x)) + c then f(x) = ln(x) \n" ); document.write( "

Algebra.Com's Answer #780418 by Edwin McCravy(20055) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "We work backwards using \"if and ONLY if\" between steps:\r\n" );
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document.write( "First we only observe (not assume!!) about the answer we are supposed to get,\r\n" );
document.write( "which is this:\r\n" );
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document.write( "that we could have gotten that if and ONLY if this were true:\r\n" );
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document.write( "And we could have gotten that if and ONLY if this were true:\r\n" );
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document.write( "But we know that would have been true if and ONLY if\r\n" );
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document.write( "were true.  But that IS GIVEN true, so  \r\n" );
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document.write( "must be true. \r\n" );
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document.write( "PROVED!\r\n" );
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document.write( "Edwin

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