SOLUTION: find the sum if it exists 25+5+1+...

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Question 1061725: find the sum if it exists
25+5+1+...
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
25+5+1+...

a%5B1%5D%22%22=%22%2225

r%22%22=%22%22%22%22=%22%22a%5B2%5D%2Fa%5B1%5D%22%22=%22%225%2F25%22%22=%22%221%2F5

r%22%22=%22%22%22%22=%22%22a%5B3%5D%2Fa%5B2%5D%22%22=%22%221%2F5

S%5Binfinity%5D%22%22=%22%22a%5B1%5D%2F%281-r%29

S%5Binfinity%5D%22%22=%22%2225%2F%281-1%2F5%29

Multiply top and bottom by 5

S%5Binfinity%5D%22%22=%22%225%2A25%2F%285%281-1%2F5%29%29

S%5Binfinity%5D%22%22=%22%22125%2F%285-1%29

S%5Binfinity%5D%22%22=%22%22125%2F4%22%22=%22%2231%261%2F4

Edwin