document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1185343>Question 1185343</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please check the document for the question: \r<BR>\n" );
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document.write( "https://docs.google.com/document/d/1Cl3HrcoR6jibNzxfDTIilS3imSplLY8nQUU0OpU9vLA/edit?usp=sharing </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #816165 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=816165\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The definition<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u%28n%2B1%29=u%28n%29%2B4 ALIGN=MIDDLE  ALT=\"u%28n%2B1%29=u%28n%29%2B4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "means each term is 4 more than the preceding term.<br><BR>\n" );
document.write( "You are given u(1)=10, so the sequence is<br><BR>\n" );
document.write( "10, 14, 18, 22, ...<br><BR>\n" );
document.write( "The problem asks for the sum of the first 20 terms.<br><BR>\n" );
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document.write( "With a common difference of 4 between successive terms, the sequence is arithmetic.<br><BR>\n" );
document.write( "The sum of any set of numbers is the number of numbers, multiplied by the average of the numbers.<br><BR>\n" );
document.write( "In an arithmetic sequence, because of the common difference between terms, the average of all the terms is the average of the first and last terms.<br><BR>\n" );
document.write( "The last (20th) term is the first term 10, plus the common difference 19 times:  u(20)=10+19(4)=86<br><BR>\n" );
document.write( "So the sum of the first 20 terms in this sequence is the number of terms (20), multiplied by the average of the first and last terms ((10+86)/2=48).<br><BR>\n" );
document.write( "ANSWER: 20*48 = 960<br><BR>\n" );
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