document.write( "Question 117751: 2, 6 , 18 , 54 , ....
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document.write( " In the sequence above what would be the 8th term? \n" );
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Algebra.Com's Answer #85721 by jim_thompson5910(35256)![]() ![]() ![]() You can put this solution on YOUR website! Notice that each term is increasing quickly. So this sequence might be a geometric sequence. To find out, let's simply divide the terms.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "First divide the 2nd term 6 by the 1st term 2 to get \r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "Now divide the 3rd term 18 by the 2nd term 6 to get \r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "Now divide the 4th term 54 by the 3rd term 18 to get \r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r \n" ); document.write( "\n" ); document.write( "So if we pick any term and divide it by the previous term, we'll always get 3. This is the common ratio between the terms. So this means that \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now since we've started at 2, this means that \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Since the general geometric sequence is \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Notice if we let n=0, we get\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "and if we let n=1, we get\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "and this generates the sequence 2, 6 , 18 , 54 , ....\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So to find the 8th term, let n=7 (remember, we started at n=0)\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So the eighth term is 4,374 \n" ); document.write( " \n" ); document.write( " |