document.write( "Question 121106: What function represents the geometric sequence ( 3,15,75,375,...)? \n" ); document.write( "
Algebra.Com's Answer #88840 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "Notice that each term is increasing exponentially. So this sequence might be a geometric sequence. To find out, let's simply divide the terms.\r
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\n" ); document.write( "\n" ); document.write( "First divide the 2nd term 15 by the 1st term 3 to get \r
\n" ); document.write( "\n" ); document.write( "\"15%2F3=5\" \r
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\n" ); document.write( "Now divide the 3rd term 75 by the 2nd term 15 to get \r
\n" ); document.write( "\n" ); document.write( "\"75%2F15=5\" \r
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\n" ); document.write( "Now divide the 4th term 375 by the 3rd term 75 to get \r
\n" ); document.write( "\n" ); document.write( "\"375%2F75=5\" \r
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\n" ); document.write( "\n" ); document.write( "So if we pick any term and divide it by the previous term, we'll always get 5. This is the common ratio between the terms. So this means that \"r=5\".\r
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\n" ); document.write( "\n" ); document.write( "Now since we've started at 3, this means that \"a=3\"\r
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\n" ); document.write( "\n" ); document.write( "Since the general geometric sequence is \"a%5Bn%5D=ar%5En\", this means the sequence is\r
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\n" ); document.write( "\n" ); document.write( "\"a%5Bn%5D=3%2A5%5En\"\r
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\n" ); document.write( "\n" ); document.write( "Check:\r
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\n" ); document.write( "\n" ); document.write( "Notice when n=0, then \r
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\n" ); document.write( "\n" ); document.write( "\"a%5B0%5D=3%2A5%5E0=3%2A1=3\"\r
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\n" ); document.write( "\n" ); document.write( "and when n=1, then \r
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\n" ); document.write( "\n" ); document.write( "\"a%5B1%5D=3%2A5%5E1=3%2A5=15\"\r
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\n" ); document.write( "\n" ); document.write( "and when n=2, then \r
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\n" ); document.write( "\n" ); document.write( "\"a%5B2%5D=3%2A5%5E2=3%2A25=75\"\r
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\n" ); document.write( "\n" ); document.write( "and when n=3, then \r
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\n" ); document.write( "\n" ); document.write( "\"a%5B3%5D=3%2A5%5E3=3%2A125=375\"\r
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\n" ); document.write( "\n" ); document.write( "and so on....
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