document.write( "Question 1146572: the tens digits of a certain number is 7 less than the units digit .the sum of the squares of the two digits is 85.find the number.with justification \n" ); document.write( "
Algebra.Com's Answer #767844 by Edwin McCravy(20062)\"\" \"About 
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the tens digits of a certain number is 7 less than the units digit.
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document.write( "                  t = u - 7
the sum of the squares of the two digits is 85.
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document.write( "            t² + u² = 85\r\n" );
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document.write( "Substitute (u - 7) for t:\r\n" );
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document.write( "      (u - 7)² + u² = 85\r\n" );
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document.write( "(u - 7)(u - 7) + u² = 85\r\n" );
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document.write( " u² - 14u + 49 + u² = 85\r\n" );
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document.write( "     2u² - 14u + 49 = 85\r\n" );
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document.write( "     2u² - 14u - 36 = 0\r\n" );
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document.write( "Divide through by 2\r\n" );
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document.write( "       u² - 7u - 18 = 0 \r\n" );
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document.write( "Factor:\r\n" );
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document.write( "     (u + 2)(u - 9) = 0\r\n" );
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document.write( " u + 2 = 0;   u - 9 = 0\r\n" );
document.write( "     u = -2;      u = 9\r\n" );
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document.write( "discard negative answer.\r\n" );
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document.write( "u = 9, substitute in\r\n" );
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document.write( "                 t = u - 7\r\n" );
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document.write( "                 t = 9 - 7\r\n" );
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document.write( "                 t = 2\r\n" );
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document.write( "            NUMBER = 29\r\n" );
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document.write( "Edwin

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