document.write( "Question 175168: An infinite geometric series has 1 and 1/5 as its first two terms: 1, 1/5, 1/25, 1/125,... what is the sum, S, of the infinite series? \n" ); document.write( "
Algebra.Com's Answer #130240 by jim_thompson5910(35256)\"\" \"About 
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The sequence that generates 1, 1/5, 1/25, 1/125,... is \"a%5Bn%5D=%281%2F5%29%5En\". Take note that the sequence is in the form \"a%5Bn%5D=a%2Ar%5En\" where \"a=1\" and \"r=1%2F5\".\r
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\n" ); document.write( "\n" ); document.write( "Remember, the formula for the sum of an infinite series is\r
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\n" ); document.write( "\n" ); document.write( "\"S=a%2F%281-r%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"S=1%2F%281-1%2F5%29\" Plug in \"a=1\" and \"r=1%2F5\"\r
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\n" ); document.write( "\n" ); document.write( "\"S=1%2F%284%2F5%29\" Subtract\r
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\n" ); document.write( "\n" ); document.write( "\"S=5%2F4\" Invert the fraction and multiply\r
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\n" ); document.write( "\n" ); document.write( "So the answer is \"S=5%2F4\" which means that 1+1/5+1/25+1/125+...=5/4
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