document.write( "Question 1154055: -39, -44, -49, -54, ...\r
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Algebra.Com's Answer #776414 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "There are 2 ways to do this kind of problem. \r
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\n" ); document.write( "\n" ); document.write( "The first method involves listing out 35 terms, each new term is found by subtracting 5 from the previous term (eg: -39 - 5 = -44, or -44-5 = -49, and so on). This is not recommended because there are so many terms. It's easy to lose track. \r
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\n" ); document.write( "\n" ); document.write( "A much better method is to use the general nth term formula of an arithmetic sequence. That formula is
\n" ); document.write( "\"a%5Bn%5D+=+a%5B1%5D+%2B+d%28n-1%29\"
\n" ); document.write( "The first term is \"a%5B1%5D+=+-39\". The common difference is \"d+=+-5\" since we add on -5 each time, or subtract 5 each time, to get the next term. \r
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\n" ); document.write( "\n" ); document.write( "So,
\n" ); document.write( "\"a%5Bn%5D+=+a%5B1%5D+%2B+d%28n-1%29\" \r
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\n" ); document.write( "\n" ); document.write( "\"a%5Bn%5D+=+-39+%2B+%28-5%29%28n-1%29\" \r
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\n" ); document.write( "\n" ); document.write( "\"a%5Bn%5D+=+-39-5n%2B5\" \r
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\n" ); document.write( "\n" ); document.write( "\"a%5Bn%5D+=+-5n-34\"\r
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\n" ); document.write( "\n" ); document.write( "As a check, let's plug in a random positive integer between 1 and 4 to see if it matches up with the proper element in the sequence we're given. I'll do n = 3
\n" ); document.write( "\"a%5Bn%5D+=+-5n-34\" \r
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\n" ); document.write( "\n" ); document.write( "\"a%5B3%5D+=+-5%283%29-34\" Replace n with 3\r
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\n" ); document.write( "\n" ); document.write( "\"a%5B3%5D+=+-15-34\" \r
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\n" ); document.write( "\n" ); document.write( "\"a%5B3%5D+=+-49\" \r
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\n" ); document.write( "\n" ); document.write( "The third term is -49\r
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\n" ); document.write( "\n" ); document.write( "Sure enough, the third term of the given sequence {-39, -44, -49, -54, ...} is -49. I'll let you check the other values of n (1, 2 and 4) to see if things line up properly or not.\r
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\n" ); document.write( "\n" ); document.write( "Once we know the nth term formula, we plug in n = 35 to get the 35th term of the arithmetic sequence
\n" ); document.write( "\"a%5Bn%5D+=+-5n-34\" \r
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\n" ); document.write( "\n" ); document.write( "\"a%5B35%5D+=+-5%2835%29-34\" Replace n with 35\r
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\n" ); document.write( "\n" ); document.write( "\"a%5B35%5D+=+-175-34\" \r
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\n" ); document.write( "\n" ); document.write( "\"a%5B35%5D+=+-209\" \r
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\n" ); document.write( "\n" ); document.write( "The 35th term is -209
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