Question

find sum of the first 10terms of geometric series with a2=1/2 and r=2

Answer 1

If a(2) = 1/2 , with r = 1/2

then a(1/2)r = 1/2
and a = 1
now just use the formula
sum(10) = 1( 1 - (1/2)^10)/(1-1/2)
= (1 - 1/1024)/(1/2)
= 2(1023/1024)
= 1023/512