Question

What is the sum of the geometric sequence 1, 4, 16, ... if there are 8 terms? A.21,845 B.43,690 C.65,535 D.87,380

Answer 1

Hi,

Answer A: 21845

Explanation:

`4^0+4^1+4^2+...+4^7=\displaystyle \sum_(i=0)^7 4^i\\=(4^8 -1)/(4-1)=(65535)/(3)=21845\\`