document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1191407>Question 1191407</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the sum of AP whose first term is 60 and last term is -104 </SPAN>\n" );
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document.write( "Not enough information.  We need some information from which we can determine the number of terms.<br><BR>\n" );
document.write( "The sum of the terms of an AP is the number of terms, multiplied by the average of all the terms; and in an AP the average of all the terms is the average of the first and last terms.<br><BR>\n" );
document.write( "The average of the first and last terms in this example is (60-104)/2 = -22.<br><BR>\n" );
document.write( "So if the number of terms is n, the sum of the terms is -22n.<br><BR>\n" );
document.write( "2 terms: 60, -104<BR>\n" );
document.write( "sum: -44 = 2(-22)<br><BR>\n" );
document.write( "3 terms: 60,-22,-104<BR>\n" );
document.write( "sum: -66 = 3(-22)<br><BR>\n" );
document.write( "4 terms: 60,16/3,-148/3,-104<BR>\n" );
document.write( "sum: -88 = 4(-22)<br><BR>\n" );
document.write( "etc....<br><BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );