document.write( "Question 1102476: The 5th term in a sequence is 25, and each term is 3 less than the previous term. Write an explicit rule and a recursive rule to describe the sequence. \n" ); document.write( "
Algebra.Com's Answer #717173 by KMST(5328)\"\" \"About 
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WITHOUT MEMORIZED FORMULAS:
\n" ); document.write( "\"a%5Bn%5D=a%5Bn-1%5D-3\" or \"highlight%28a%5Bn%2B1%5D=a%5Bn%5D-3%29\"
\n" ); document.write( "would be the recursive rule spelled out in
\n" ); document.write( "\"each term is 3 less than the previous term.\"
\n" ); document.write( "Then \"n-5\" terms after the 5th term, we would have
\n" ); document.write( "subtracted from 25 \"n-5\" times 3, so
\n" ); document.write( "\"a%5Bn%5D=25-3%28n-5%29\" , which simplifies to
\n" ); document.write( "\"a%5Bn%5D=25-3n-5\" and to the simplest explicit rule
\n" ); document.write( "\"a%5Bn%5D=20-3n\" .
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\n" ); document.write( "Your teacher may have in mind a lot of formula memorizing and writing, like
\n" ); document.write( "\"d=-3\"= common difference.
\n" ); document.write( "\"a%5Bn%2B1%5D=a%5Bn%5D%2Bd\" is the memorizable recursive rule formula for any arithmetic sequence,
\n" ); document.write( "so in this case \"a%5Bn%2B1%5D=a%5Bn%5D%2B%28-3%29\" ,
\n" ); document.write( "or \"highlight%28a%5Bn%2B1%5D=a%5Bn%5D-3%29\" .
\n" ); document.write( "For all arithmetic sequences,
\n" ); document.write( "\"a%5Bn%5D=a%5B1%5D%2B%28n-1%29d\" is the memorizable explicit rule for any arithmetic sequence.
\n" ); document.write( "For \"n=5\" , with \"a%5B5%5D=25\" and \"d=-3\", we can find \"a%5B1%5D\" :
\n" ); document.write( "\"a%5B5%5D=a%5B1%5D%2B%285-1%29%28-3%29\"
\n" ); document.write( "\"25=a%5B1%5D%2B4%28-3%29\"
\n" ); document.write( "\"25=a%5B1%5D-12\"
\n" ); document.write( "\"25%2B12=a%5B1%5D\"
\n" ); document.write( "\"a%5B1%5D=37\" .
\n" ); document.write( "Plugging \"a%5B1%5D=37+and+%7B%7B%7Bd=-3\"
\n" ); document.write( "into the memorized \"a%5Bn%5D=a%5B1%5D%2B%28n-1%29d\" , we get explicit rule
\n" ); document.write( "\"highlight%28a%5Bn%5D=37-3%28n-1%29%29\" ,
\n" ); document.write( "not that simple, but maybe the expected answer.
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