document.write( "Question 683768: The operation * is defined on the set of real numbers by a*b=a+b+ab/2. Is the operation associative \n" ); document.write( "
Algebra.Com's Answer #466385 by tommyt3rd(5050)\"\" \"About 
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we check that (a*b)*c = a*(b*c)\r
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\n" ); document.write( "\n" ); document.write( "(a*b)*c = (a+b+ab/2)*c = \r
\n" ); document.write( "\n" ); document.write( "a+b+ab/2 +c + ((a+b+ab/2)c)/2=\r
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\n" ); document.write( "\n" ); document.write( "a*(b*c) = a*(b+c+bc/2) =\r
\n" ); document.write( "\n" ); document.write( "a+(b+c+bc/2)+(a((b+c+bc/2))/2\r
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\n" ); document.write( "\n" ); document.write( "comparing...\r
\n" ); document.write( "\n" ); document.write( "(a+b+ab/2 +c + ((a+b+ab/2)c)/2) -
\n" ); document.write( "(a+(b+c+bc/2)+(a((b+c+bc/2))/2)\r
\n" ); document.write( "\n" ); document.write( "which is 0\r
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\n" ); document.write( "\n" ); document.write( "the operation is associative\r
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\n" ); document.write( "\n" ); document.write( ":)
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