Question

topic: Finite Geometric Sums
what is the value of ..

Answer 1

for i=1 ===> Sum=4

for i=2===> Sum=2

for I=3===> Sum=1

Hence the answer is 7

Or you could have use the Sum formula of a GP:

Sum = a(1-r)^n/(1-r), with a=1, r=1/2 & n=3