document.write( "Question 1061353: If f(x) = (x-3) logx, then prove the equation xlogx = 3-x is satisfied by at least one value of x lying between 1 and 3. \n" ); document.write( "
Algebra.Com's Answer #676150 by Edwin McCravy(20059)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "This problem might as well be stated:\r\n" );
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document.write( "\"If the capital of Georgia is Atlanta, then prove the equation \r\n" );
document.write( "xlogx = 3-x is satisfied by at least one value of x lying \r\n" );
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document.write( "That's because \"f(x) = (x-3)logx\" has no more to do with whether\r\n" );
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document.write( "\"the equation xlogx = 3-x is satisfied by at least one value of x \r\n" );
document.write( "lying between 1 and 3\" than the capital of Georgia being Atlanta \r\n" );
document.write( "has to do with it!\r\n" );
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document.write( "Thus we ignore the f(x) part and take the problem to be:\r\n" );
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document.write( "Prove that the equation \r\n" );
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document.write( "\"x%2Alog%28%28x%29%29+=+3-x\" \r\n" );
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document.write( "is satisfied by at least one value of x lying between 1 and 3.\r\n" );
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document.write( "Consider the function which is continuous on [1,3]\r\n" );
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document.write( "\"g%28x%29=x%2Alog%28%28x%29%29-3%2Bx\"\r\n" );
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document.write( "\"g%281%29=1%2Alog%28%281%29%29-3%2B1=-2\"\r\n" );
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document.write( "\"g%283%29=3%2Alog%28%283%29%29-3%2B3=1.4313638...\"\r\n" );
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document.write( "g(1) is negative and g(3) is positive.\r\n" );
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document.write( "Thus there is some number, say h, on [1,3] such that\r\n" );
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document.write( "\"g%28h%29=0\"\r\n" );
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document.write( "Thus\r\n" );
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document.write( "\"g%28h%29=h%2Alog%28%28h%29%29-3%2Bh=0\"\r\n" );
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document.write( "and\r\n" );
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document.write( "\"h%2Alog%28%28h%29%29+=+3-h\"\r\n" );
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document.write( "[Note: If you require that h be an algebraic number then\r\n" );
document.write( "choose h to be \"root%285%2C100%29\"]\r\n" );
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document.write( "Edwin
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