Question

How to express this series in summation notation? 27+18+12+8

Answer 1

The answer is `=sum_(k=0)^3 2^k*3^(3-k)`

Explanation:

The sum is

`S=(2^0xx3^3)+(2^1xx3^2)+(2^2xx3^1)+(2^3xx3^0)`

`=sum_(k=0)^3 2^k*3^(3-k)`