document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=772070>Question 772070</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 25+28+31+.....+100 to solve the sum </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #470659 by </B><A HREF=/tutors/aboutme.mpl?userid=John10><B>John10(297)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=John10><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=John10><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=470659\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Hi,\r<BR>\n" );
document.write( "\n" );
document.write( "This is arithmetic sequence because the common difference:\r<BR>\n" );
document.write( "\n" );
document.write( " d = 28 - 25 = 31- 28 =...= 3\r<BR>\n" );
document.write( "\n" );
document.write( "Apply the formula\r<BR>\n" );
document.write( "\n" );
document.write( "a(n) = a(1) + (n- 1)d\r<BR>\n" );
document.write( "\n" );
document.write( "100 = 25 + (n - 1)3\r<BR>\n" );
document.write( "\n" );
document.write( "100 = 25 + 3n - 3\r<BR>\n" );
document.write( "\n" );
document.write( "3n - 3 = 75\r<BR>\n" );
document.write( "\n" );
document.write( "3n = 78\r<BR>\n" );
document.write( "\n" );
document.write( "n = 26\r<BR>\n" );
document.write( "\n" );
document.write( "So we have 26 terms totally\r<BR>\n" );
document.write( "\n" );
document.write( "To find the sum, apply the formula:\r<BR>\n" );
document.write( "\n" );
document.write( "S(n) = n(a(1) + a(n))/2<BR>\n" );
document.write( "     = (26/2)( 25 + 100)<BR>\n" );
document.write( "     = (13)(125)<BR>\n" );
document.write( "     = 1625\r<BR>\n" );
document.write( "\n" );
document.write( "Hope it helps you!\r<BR>\n" );
document.write( "\n" );
document.write( "John10 (john100185@yahoo.com) </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );