document.write( "Question 550239: the sum of a geometric series of 6 terms with ratio 2 is negative 189. what is the first term? \n" ); document.write( "

Algebra.Com's Answer #358658 by TutorDelphia(193) $\"\"$ $\"About$

You can put this solution on YOUR website!
First we need to know the formula of a geometric series:\r
\n" ); document.write( "\n" ); document.write( "Its\r
\n" ); document.write( "\n" ); document.write( " $\"s=a%28%281-r%5En%29%2F%281-r%29%29\"$
\n" ); document.write( "Where s=sum, a=the first term r is the ratio and n is the number of terms\r
\n" ); document.write( "\n" ); document.write( "We know most of the info already
\n" ); document.write( " $\"-189=a%28%281-2%5E6%29%2F%281-2%29%29\"$
\n" ); document.write( "-189=a(1-64)/-1
\n" ); document.write( " $\"-189=a%2A-63%2A-1\"$
\n" ); document.write( " $\"-189=a%2A63\"$
\n" ); document.write( "a=-3\r
\n" ); document.write( "\n" ); document.write( "You won't have to do this step, but to get a feel for the series, here's our terms -3,-6,-12,-24,-48,-96 and they do equal -189 \n" ); document.write( "

\n" );