document.write( "Question 1134943: The sum of an arithmetic series is 100 times the value of its first term, while the last term is 9 times the first term. Calculate the number of terms in the series if the first term is not equal to zero. \n" ); document.write( "
Algebra.Com's Answer #752444 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
Formula for sum:
\n" ); document.write( "\"+s+=+a%2A+%28+1-r%5En%29++%2F+%28+1+-+r+%29+\"
\n" ); document.write( "----------------------------------
\n" ); document.write( "\"+100a+=+a%2A%28+1-r%5En%29++%2F+%28+1+-+r+%29+\"
\n" ); document.write( "\"+a%2Ar%5En+=+9a+\"
\n" ); document.write( "\"+r%5En+=+9+\"
\n" ); document.write( "---------------------
\n" ); document.write( "\"+100+=+%28+%28+1-r%5En%29+%29+%2F+%28+1+-+r+%29+\"
\n" ); document.write( "\"+100+=++%28+1+-+9+%29+%2F+%28+1+-+r+%29+\"
\n" ); document.write( "\"+1+-+r+=+-8+%2F+100+\"
\n" ); document.write( "\"+-r+=+-.08+-+1+\"
\n" ); document.write( "\"+r+=+1.08+\"
\n" ); document.write( "-------------------
\n" ); document.write( "\"+1.08%5En+=+9+\"
\n" ); document.write( "\"+n%2Alog%28+1.08+%29+=+log%289%29+\"
\n" ); document.write( "\"+n+=+log%289%29%2Flog%28+1.08+%29+\"
\n" ); document.write( "\"+n+=+log%289%29%2Flog%281.08%29+\"
\n" ); document.write( "\"+n+=+.9542425+%2F+.0334238+\"
\n" ); document.write( "\"+n+=+28.55+\"
\n" ); document.write( "29 terms
\n" ); document.write( "---------------
\n" ); document.write( "check:
\n" ); document.write( "\"+100+=+%28+%28+1-r%5En%29+%29+%2F+%28+1+-+r+%29+\"
\n" ); document.write( "\"+100+=+%28+%28+1-1.08%5E29%29+%29+%2F+%28+1+-+1.08+%29+\"
\n" ); document.write( "\"+100+=++%28+1+-+9.31727+%29+%2F+%28-.08%29+\"
\n" ); document.write( "\"+100+=+8.31727+%2F+.08+\"
\n" ); document.write( "\"+100+=+103.96+\"
\n" ); document.write( "I used \"+29+\" instead of \"+28.55+\"
\n" ); document.write( "That's the error, I think. Definitely get
\n" ); document.write( "a 2nd opinion on this.
\n" ); document.write( "
\n" );