express the following sum using summation (aka sigma) notation:

Question

1/8 + 1/4 + 1/2 + 1 +2 + 4 + 8 + 16

Answer 1

Just by looking at the consecutive integers, the common ratio is 2.  The first term is 1/8.  You also have 8 terms in the sum.

 

The sigma notation is then the finite sum of the series.

 

8

 ∑(1/8)(2)^{n - 1}

n=1