SOLUTION: The first and 3rd terms of a GP are 2 and 1/9,respectively. Find: a) the common ratio b) the sum of the first 5 terms.

Algebra ->  Sequences-and-series -> SOLUTION: The first and 3rd terms of a GP are 2 and 1/9,respectively. Find: a) the common ratio b) the sum of the first 5 terms.      Log On


   

Question 1157938: The first and 3rd terms of a GP are 2 and 1/9,respectively. Find:
a) the common ratio
b) the sum of the first 5 terms.
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
2r%5E2=1%2F9

Common Ratio, r:
r%5E2=1%2F18
r=sqrt%281%2F%282%2A9%29%29
r=%281%2F3%29sqrt%281%2F2%29
r=%281%2F3%29sqrt%281%2F2%29sqrt%282%2F2%29
r=%281%2F3%29%281%2F2%29sqrt%282%29
highlight%28r=sqrt%282%29%2F6%29


Sum of First Five Terms
2%28%281-%28sqrt%282%29%2F6%29%5E5%29%2F%281-sqrt%282%29%2F6%29%29
.
.