document.write( "Question 102758: 1.[A]the 18th term of an arithmetic progression is 25.find it 1st term if is common is 2? [b1]find the common ratio[b2]the 8th term [b3]nth term of the geometric progression \n" ); document.write( "
Algebra.Com's Answer #74723 by stanbon(75887)\"\" \"About 
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1.[A]the 18th term of an arithmetic progression is 25.find it 1st term if is common is 2? [b1]find the common ratio[b2]the 8th term [b3]nth term of the geometric progression \r
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\n" ); document.write( "Comment: I'm not sure I understand your question.
\n" ); document.write( "#1. You have an arithmetic progression where a(18)=25 ; you want to find
\n" ); document.write( "the 1st term if the common difference is 2. If that is the question,
\n" ); document.write( "a(18) = a(1)+17d
\n" ); document.write( "25 = a(1) + 34
\n" ); document.write( "a(1) = -9
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\n" ); document.write( "#2. Now you are talking about a geometric progression and you want to
\n" ); document.write( "find the ratio of the 8th term to the nth term. If that is the question
\n" ); document.write( "a(8)/a(n) = [1-r^9] /[1-r^(n+1)]\r
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.\r
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