document.write( "Question 1168642: If for three distinct positive numbers x, y, and z,
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Algebra.Com's Answer #793283 by ikleyn(52782)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "If for three distinct positive numbers x, y, and z,
\n" ); document.write( "\"y%2F%28x-z%29\" = \"%28x%2By%29%2Fz\" = \"x%2Fy\"
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document.write( "You are given two equations\r\n" );
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document.write( "    \"y%2F%28x-z%29\" = \"x%2Fy\"         (1)\r\n" );
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document.write( "    \"%28x%2By%29%2Fz\" = \"x%2Fy\"         (2)\r\n" );
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document.write( "In equation (1), divide the numerator and denominator of the left side by \"y\".\r\n" );
document.write( "    You can safely do it, because \"y\" is assumed to be positive.\r\n" );
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document.write( "In equation (2), divide the numerator and denominator of the left side by \"y\".\r\n" );
document.write( "    You can safely do it, due to the same reason.\r\n" );
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document.write( "Both left side sides in equations (1) and (2) will not change their values, so you will get an EQUIVALENT equations\r\n" );
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document.write( "    \"1%2F%28x%2Fy+-+z%2Fy%29\" = \"x%2Fy\"        (1')\r\n" );
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document.write( "    \"%28x%2Fy+%2B+1%29%2F%28%28z%2Fy%29%29\" = \"x%2Fy\"        (2')\r\n" );
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document.write( "Introduce new variables  u = \"x%2Fy\"  and  v = \"z%2Fy\".\r\n" );
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document.write( "Our goal is to find the numerical value of  \"u\".\r\n" );
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document.write( "You can write equation (1') and (2') in the form\r\n" );
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document.write( "    \"1%2F%28u-v%29\" = u              (3)\r\n" );
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document.write( "    \"%28u%2B1%29%2Fv\" = u              (4)\r\n" );
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document.write( "From equation (3), you have\r\n" );
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document.write( "    u*(u-v) = 1.             (5)\r\n" );
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document.write( "From equation (4) express  v = \"%28u%2B1%29%2Fu\"  and substitute it into equation (5), replacing \"v\" there.  You will get\r\n" );
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document.write( "    \"u%2A%28u+-+%28u%2B1%29%2Fu%29\" = 1,       or\r\n" );
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document.write( "    \"u%2A%28%28u%5E2+-+u+-+1%29%2Fu%29\" = 1,    or\r\n" );
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document.write( "    \"u%5E2+-+u+-1\" = 1,           or\r\n" );
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document.write( "    \"u%5E2+-+u+-+2\" = 0.          (6)\r\n" );
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document.write( "Equation (6) is a quadratic equation.  Solve it by factoring\r\n" );
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document.write( "    (u-2)*(u+1) = 0.\r\n" );
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document.write( "Thus it has two roots  u= 2  and  u= -1.\r\n" );
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document.write( "According to the condition, only positive value  u= 2  is the solution to the problem.\r\n" );
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document.write( "So, the ANSWER  to the problem's question is  \"x%2Fy\" = u = 2.\r\n" );
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