document.write( "Question 997593: find the sum S8 for the geometric series 6-1.8+0.54-0.162+... \n" ); document.write( "
Algebra.Com's Answer #618127 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
6-1.8+0.54-0.162+...
\n" ); document.write( "
\r\n" );
document.write( "\"matrix%281%2C2%2C2nd%2Cterm%29%2Fmatrix%281%2C2%2C1st%2Cterm%29=%28-1.8%29%2F6=-0.3\"\r\n" );
document.write( "\r\n" );
document.write( "\"matrix%281%2C2%2C3rd%2Cterm%29%2Fmatrix%281%2C2%2C2nd%2Cterm%29=0.54%2F%28-1.8%29=-0.3\"\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "So there is a common ratio of -0.3.  This is a geometric \r\n" );
document.write( "series with r=-0.3 and first term a1=6.\r\n" );
document.write( "\r\n" );
document.write( "Substitute those with n=8 in the sum formula:\r\n" );
document.write( "\r\n" );
document.write( "\"S%5Bn%5D=%28a%5B1%5D%281-r%5En%29%29%2F%281-r%29\"\r\n" );
document.write( "\r\n" );
document.write( "\"S%5B8%5D=%286%281-%28-0.3%29%5E8%29%29%2F%281-%28-0.3%29%29\"\r\n" );
document.write( "\r\n" );
document.write( "\"S%5B8%5D=%286%281-%28-0.3%29%5E8%29%29%2F%281%2B0.3%29\"\r\n" );
document.write( "\r\n" );
document.write( "\"S%5B8%5D=%286%281-%28-0.3%29%5E8%29%29%2F1.3\"\r\n" );
document.write( "\r\n" );
document.write( "\"S%5B8%5D=4.6150818\"\r\n" );
document.write( "\r\n" );
document.write( "Edwin
\n" ); document.write( "
\n" );