document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=485370>Question 485370</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Respected Sir / Mam ,<BR>\n" );
document.write( "Please help me to solve this question. I will be very grateful for your help .<BR>\n" );
document.write( "My question is :<BR>\n" );
document.write( "Which term of the progression - 1, -3,-5 .... is -39 ?\r<BR>\n" );
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document.write( "As the answer given  is : 20th<BR>\n" );
document.write( "Please provide me the steps for this question.\r<BR>\n" );
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document.write( "Thank you<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #331974 by </B><A HREF=/tutors/aboutme.mpl?userid=htmentor><B>htmentor(1343)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=htmentor><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=htmentor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=331974\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is an arithmetic sequence with common difference = -2.<BR>\n" );
document.write( "The general formula for the n-th term of an arithmetic sequence is:<BR>\n" );
document.write( "a_n = a1 + (n-1)d<BR>\n" );
document.write( "In this case, a1 = -1, d = -2, so we have:<BR>\n" );
document.write( "a_n = -1 - 2(n-1)<BR>\n" );
document.write( "We need to solve for n for a_n = -39:<BR>\n" );
document.write( "-39 = -1 - 2(n-1)<BR>\n" );
document.write( "2(n-1) = 38<BR>\n" );
document.write( "n-1 = 19<BR>\n" );
document.write( "n = 20 </SPAN>\n" );
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