document.write( "Question 1070092: How many terms of the A.P 9,17,25,...Must be taken to give a sum of 636? \n" ); document.write( "

Algebra.Com's Answer #685202 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"d=8\"$
\n" ); document.write( " $\"a%5B1%5D=9\"$
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( " $\"S%5Bn%5D=%28n%2F2%29%282%2Aa%5B1%5D%2B%28n-1%29d%29\"$
\n" ); document.write( "Substituting,
\n" ); document.write( " $\"%28n%2F2%29%282%2A9%2B%28n-1%298%29=636\"$
\n" ); document.write( " $\"n%2818%2B8n-8%29=1272\"$
\n" ); document.write( " $\"%288n%2B10%29n=1272\"$
\n" ); document.write( " $\"%284n%2B5%29n=636\"$
\n" ); document.write( " $\"4n%5E2%2B5n-636=0\"$
\n" ); document.write( " $\"%28n-12%29%284n%2B53%29=0\"$
\n" ); document.write( "We're only interested in the integer solution.
\n" ); document.write( " $\"n-12=0\"$
\n" ); document.write( " $\"n=12\"$ \r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );