Algebra.Com's Answer #658439 by ikleyn(52803)![\"\"](\"/images/stars/stars-13.gif\")  
You can put this solution on YOUR website!
.
\n" );
document.write( "(x+y)^2-(x-y)^2=72
\n" );
document.write( "In the equation above, x and y are positive integers. Which of the following CANNOT be the value of x+y?
\n" );
document.write( "A) 9
\n" );
document.write( "B) 11
\n" );
document.write( "C) 19
\n" );
document.write( "D) 24
\n" );
document.write( "~~~~~~~~~~~~~~\r
\n" );
document.write( "
\n" );
document.write( "\n" );
document.write( "\r\n" );
document.write( " = after transformations = 4xy.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "If = = 72, then 4xy = 72, then xy = 18,\r\n" );
document.write( "\r\n" );
document.write( "and for integer positive x and y we have these and only these solutions:\r\n" );
document.write( "\r\n" );
document.write( "(x,y) = (1,18), (2,9), (3,6), (6,3), (9,2) and (18,1).\r\n" );
document.write( "\r\n" );
document.write( "Then x+y has these and only these values: x+y = 19, 11, 9.\r\n" );
document.write( "\r\n" );
document.write( "It can not be 24.\r\n" );
document.write( "\r\n" );
document.write( "The answer is option D).\r\n" );
document.write( " \r
\n" );
document.write( "\n" );
document.write( "Solved.\r
\n" );
document.write( "
\n" );
document.write( "\n" );
document.write( " \n" );
document.write( " |