document.write( "Question 82149: Find the point on the positive y-axis that is a distance 5 from the point
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Algebra.Com's Answer #58847 by Edwin McCravy(20056)\"\" \"About 
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document.write( "Find the point on the positive y-axis that\r\n" );
document.write( "is a distance 5 from the point \r\n" );
document.write( "P(3,4). The answer is multiple choice. \r\n" );
document.write( "a. A(0,6)\r\n" );
document.write( "b. A(0,8)\r\n" );
document.write( "c. A(6,0)\r\n" );
document.write( "d. A(8,0)\r\n" );
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document.write( "Every point on the y-axis has 0 as its \r\n" );
document.write( "x-coordinate, which immediately\r\n" );
document.write( "rules out c and d.  \r\n" );
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document.write( "So let the desired point be A(0,y)\r\n" );
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document.write( "Use the distance formula:\r\n" );
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document.write( "d = Ö(x2-x1)² + (y2-y1)²\r\n" );
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document.write( "(x1,y1) = (3,4), (x2,y2) = (0,y), d = 5\r\n" );
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document.write( "     ___________________\r\n" );
document.write( "5 = Ö(0 - 3)² + (y - 4)²\r\n" );
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document.write( "5 = Ö(-3)² + (y - 4)²\r\n" );
document.write( "     ____________\r\n" );
document.write( "5 = Ö9 + (y - 4)²\r\n" );
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document.write( "Square both sides:\r\n" );
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document.write( "25 = 9 + (y - 4)²\r\n" );
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document.write( "16 = (y - 4)²\r\n" );
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document.write( "Take square roots of both sides\r\n" );
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document.write( "±4 = y - 4\r\n" );
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document.write( "4 ± 4 = y\r\n" );
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document.write( "Using the +, y = 8\r\n" );
document.write( "Using the -, y = 0\r\n" );
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document.write( "So there are two points on the x-axis\r\n" );
document.write( "which are 5 units from P(3,4). They\r\n" );
document.write( "are (0,8) and (0,0).  The only one\r\n" );
document.write( "listed is (0,8). So the correct choice\r\n" );
document.write( "is b.\r\n" );
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document.write( "Edwin
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