document.write( "Question 1048202: Given that a candle is 13.5 inches tall when it has been burning for 8 hours at a rate of 0.5 inches per hour,
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Algebra.Com's Answer #663782 by Edwin McCravy(20077)\"\" \"About 
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\n" ); document.write( "a candle is 13.5 inches tall when it has been burning for 8 hours
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document.write( "So when the time = 8 hours, the \r\n" );
document.write( "candle's height = 13.5 inches\r\n" );
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\n" ); document.write( "burning...at a rate of 0.5 inches per hour,
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document.write( "So when the time = 9 hours, the candle's height \r\n" );
document.write( "will be 13 inches.\r\n" );
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document.write( "Let x = the number of hours the candle has been \r\n" );
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document.write( "Let y = the height of the candle when it has been \r\n" );
document.write( "burning for x hours.\r\n" );
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document.write( "So when x = 8, y = 13.5 and\r\n" );
document.write( "when x = 9, y = 13\r\n" );
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document.write( "We want to find the equation of the line that passes\r\n" );
document.write( "through the two points (8,13.5) and (9,13)\r\n" );
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document.write( "First we use the slope formula\r\n" );
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document.write( "\"m\"\"%22%22=%22%22\"\"%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29\"\r\n" );
document.write( "where (x1,y1) = (8,13.5)\r\n" );
document.write( "and where (x2,y2) = (9,13)\r\n" );
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document.write( "\"m\"\"%22%22=%22%22\"\"%2813-13.5%29%2F%289-8%29\"\"%22%22=%22%22\"\"%28-0.5%29%2F1\"\"%22%22=%22%22\"\"-0.5%29\"\r\n" );
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document.write( "Point-slope formula:\r\n" );
document.write( "y - y1 = m(x - x1)\r\n" );
document.write( "where (x1,y1) = (8,13.5)\r\n" );
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document.write( "y - 13.5 = -0.5(x - 8)\r\n" );
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document.write( "y - 13.5 = -0.5x + 4\r\n" );
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document.write( "       y = -0.5x + 17.5\r\n" );
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\n" ); document.write( "How tall was the candle when it had been burning
\n" ); document.write( "for 2.5 hours?
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document.write( "Substitute 2.5 for x\r\n" );
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document.write( "       y = -0.5(2.5) + 17.5\r\n" );
document.write( "       y = 16.25\r\n" );
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document.write( "So the candle was 16.25 inches tall when it had been \r\n" );
document.write( "burning for only 2.5 hours.\r\n" );
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document.write( "Edwin
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