document.write( "Question 1023337: What is the sum of all of the odd numbers from 21 to 39? \n" ); document.write( "

Algebra.Com's Answer #639109 by ikleyn(52781) $\"\"$ $\"About$

You can put this solution on YOUR website!
.
\n" ); document.write( "What is the sum of all of the odd numbers from 21 to 39?
\n" ); document.write( "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "

\r\n" );
document.write( "Use the formula \r\n" );
document.write( "\r\n" );
document.write( "1 + 3 + 5 + 7 + . . . + (2n-1) = .\r\n" );
document.write( "\r\n" );
document.write( "In your case \r\n" );
document.write( "\r\n" );
document.write( "1 + 3 + 5 + 7 + . . . + 39 = ,\r\n" );
document.write( "\r\n" );
document.write( "1 + 3 + 5 + 7 + . . . + 19 = ,\r\n" );
document.write( "\r\n" );
document.write( "so\r\n" );
document.write( "\r\n" );
document.write( "the difference =  = 400 - 100 = 300.\r\n" );
document.write( "\r\n" );
document.write( "It is exactly the sum 21 + 23 + . . . + 39, and it is your answer.\r\n" );
document.write( "

\n" ); document.write( " \n" ); document.write( "

\n" );