document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=933557>Question 933557</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 4th term Of an arithmetic sequence is 17. Sum of first 20 terms is 990. Find first term and common difference. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #566875 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=566875\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 4th term Of an arithmetic sequence is 17. Sum of first 20 terms is 990. Find first term and common difference.\r<BR>\n" );
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document.write( "4th term Of an arithmetic sequence is 17.<BR>\n" );
document.write( "t4 =17<BR>\n" );
document.write( "a+3d=17.................(1)\r<BR>\n" );
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document.write( " Sum of first 20 terms is 990. <BR>\n" );
document.write( "S20 = 990\r<BR>\n" );
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document.write( "Sn = n/2(2a+(n-1)d)\r<BR>\n" );
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document.write( "20/2(2a+(20-1)d)=990<BR>\n" );
document.write( "10(2a+19d)=990<BR>\n" );
document.write( "2a+19d =99.................(2)\r<BR>\n" );
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document.write( "Sole (1) & (2)\r<BR>\n" );
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document.write( "a+3d=17<BR>\n" );
document.write( "multiply by -2<BR>\n" );
document.write( "-2a-6d=-34<BR>\n" );
document.write( "add this equation to (2)\r<BR>\n" );
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document.write( "13d=65<BR>\n" );
document.write( "d=5<BR>\n" );
document.write( "a+3d=17<BR>\n" );
document.write( "a+15=17<BR>\n" );
document.write( "a=2\r<BR>\n" );
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document.write( "2,7,12,17,.........\r<BR>\n" );
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document.write( "Find first term and common difference. </SPAN>\n" );
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