document.write( "Question 568361: find the sum of the integers 1to50 inclusive \n" ); document.write( "
Algebra.Com's Answer #366926 by Edwin McCravy(20060)![]() ![]() You can put this solution on YOUR website! \r\n" ); document.write( "Let the sum be S\r\n" ); document.write( "\r\n" ); document.write( " S = 1 + 2 + 3 + ... + 48 + 49 + 50 <-- there are 50 terms\r\n" ); document.write( " S = 50 + 49 + 48 + ... + 3 + 2 + 1 <-- there are 50 terms\r\n" ); document.write( " \r\n" ); document.write( "add the two equations term by term:\r\n" ); document.write( "\r\n" ); document.write( " S = 1 + 2 + 3 + ... + 48 + 49 + 50 <-- there are 50 terms\r\n" ); document.write( " S = 50 + 49 + 48 + ... + 3 + 2 + 1 <-- there are 50 terms\r\n" ); document.write( "2S = 51 + 51 + 51 + ... + 51 + 51 + 51 <-- there are 50 terms\r\n" ); document.write( "2S = 51×50 <--51 times 50 because there are 50 51's added together \r\n" ); document.write( "2S = 2550\r\n" ); document.write( " S = 1275 \r\n" ); document.write( "\r\n" ); document.write( "Or by formula:\n" ); document.write( " |