document.write( "Question 1048381: In the graph y=3^x, read the approximate value of x when y = 5 (1dp)
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Algebra.Com's Answer #663955 by Edwin McCravy(20062)\"\" \"About 
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document.write( "We draw a green vertical line from the point where y=5 on the\r\n" );
document.write( "red line where the graph of y = 3x crosses it:\r\n" );
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document.write( "Then we look down at the x-axis and see that the green line\r\n" );
document.write( "touches the x-axis at a little bit less than 1.5, maybe about \r\n" );
document.write( "1.46.  It's actually 1.464973521 which can be calculated with\r\n" );
document.write( "logarithms.\r\n" );
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document.write( "\"3%5Ex\"\"%22%22=%22%22\"\"5\"\r\n" );
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document.write( "Take the logs of both sides:\r\n" );
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document.write( "\"log%28%283%5Ex%29%29\"\"%22%22=%22%22\"\"log%28%285%29%29\"\r\n" );
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document.write( "Use the property of logs \"log%28%28B%5EA%29%29=B%2Alog%28%28A%29%29\" \r\n" );
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document.write( "\"x%2Alog%28%283%29%29\"\"%22%22=%22%22\"\"log%28%285%29%29\"\r\n" );
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document.write( "Divide both sides by log(3)\r\n" );
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document.write( "\"x\"\"%22%22=%22%22\"\"log%28%285%29%29%2Flog%28%283%29%29\"\"%22%22=%22%22\"\"0.6989700043%2F0.4771212547\"\"%22%22=%22%22\"\"1.464973521\" \r\n" );
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document.write( "If we do the same with the graph of y = 3-x, it just\r\n" );
document.write( "puts it \"in the mirror\", i.e., reflects across the y-axis, and\r\n" );
document.write( "the value of x is just the negative of what it was above.\r\n" );
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document.write( "Edwin
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