document.write( "Question 332879: find N of the arithmetic sequence a1=-6, aN=-23, d=-1 \n" ); document.write( "

Algebra.Com's Answer #238506 by jrfrunner(365) $\"\"$ $\"About$

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in an arithmetic sequence, \r
\n" ); document.write( "\n" ); document.write( "the nth term is defined as : $\"a%5Bn%5D=a1%2B%28n-1%29%2Ad\"$
\n" ); document.write( "therefore\r
\n" ); document.write( "\n" ); document.write( "given: $\"a%5B1%5D=-6\"$ , $\"a%5Bn%5D=+-23\"$ and d = -1, substitute into $\"a%5Bn%5D=a%5B1%5D%2B%28n-1%29%2Ad\"$ and solve for n\r
\n" ); document.write( "\n" ); document.write( "-23=-6+(n-1)*(-1)
\n" ); document.write( "-23+6=-(n-1)
\n" ); document.write( "17=n-1
\n" ); document.write( "18=n\r
\n" ); document.write( "\n" ); document.write( "---
\n" ); document.write( "so, $\"a%5B18%5D=-23\"$ is the 18th term. \n" ); document.write( "

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