document.write( "Question 979019: If the first two terms of a geometric sequence are 2 and 1, respectively, which term of the sequence is equal to 1/16? \n" ); document.write( "
Algebra.Com's Answer #600334 by MathLover1(20850)\"\" \"About 
You can put this solution on YOUR website!
In a Geometric Sequence each term is found by multiplying the previous term by a constant.\r
\n" ); document.write( "\n" ); document.write( "In general we write a Geometric Sequence like this:\r
\n" ); document.write( "\n" ); document.write( "{ \"a\", \"ar\", \"ar%5E2\", \"ar%5E3\", ... }\r
\n" ); document.write( "\n" ); document.write( "where:\r
\n" ); document.write( "\n" ); document.write( " \"a\" is the first term, and
\n" ); document.write( " \"r\" is the factor between the terms (called the \"common ratio\")\r
\n" ); document.write( "\n" ); document.write( "so, if first term is \"a=2\" and second term is \"ar=1\", a constant (the \"common ratio\") is \"r=1%2F2\"\r
\n" ); document.write( "\n" ); document.write( "and your sequence looks like this:
\n" ); document.write( "{ \"2\", \"1\", \"2%2A%281%2F2%29%5E2\", \"2%2A%281%2F2%29%5E3\", \"2%2A%281%2F2%29%5E4\",\"2%2A%281%2F2%29%5E5\",\"2%2A%281%2F2%29%5E6\"... }\r
\n" ); document.write( "\n" ); document.write( "so, we can find out which term is \"1%2F16\" using the rule\r
\n" ); document.write( "\n" ); document.write( "to calculate any term:\r
\n" ); document.write( "\n" ); document.write( "\"a%5Bn%5D+=+ar%5E%28n-1%29\"\r
\n" ); document.write( "\n" ); document.write( "(We use \"n-1\" because \"ar%5E0\" is for the 1st term)\r
\n" ); document.write( "\n" ); document.write( "\"a%5Bn%5D+=+1%2F16\"
\n" ); document.write( "\"ar%5E%28n-1%29=1%2F16\"\r
\n" ); document.write( "\n" ); document.write( "\"2%2A%281%2F2%29%5E%28n-1%29=1%2F16\"\r
\n" ); document.write( "\n" ); document.write( "\"%281%2F2%29%5E%28n-1%29=1%2F32\"\r
\n" ); document.write( "\n" ); document.write( "\"%281%2F2%29%5E%28n-1%29=1%2F2%5E5\"\r
\n" ); document.write( "\n" ); document.write( "\"%281%2F2%29%5E%28n-1%29=%281%2F2%29%5E5\"\r
\n" ); document.write( "\n" ); document.write( "\"n-1=5\"\r
\n" ); document.write( "\n" ); document.write( "\"n=5%2B1\"\r
\n" ); document.write( "\n" ); document.write( "=> \"n=6\"......so, it is \"6th\" term\r
\n" ); document.write( "\n" ); document.write( "check:\r
\n" ); document.write( "\n" ); document.write( "{ \"2\", \"1\", \"2%281%2F4%29\", \"2%2A%281%2F8%29\", \"2%2A%281%2F16%29\",\"2%2A%281%2F32%29\",\"2%2A%281%2F64%29\",... }\r
\n" ); document.write( "\n" ); document.write( "{ \"2\", \"1\", \"1%2F2\", \"1%2F4\", \"1%2F8\",\"highlight%281%2F16%29\",\"1%2F32\",... }\r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );