Question

prove that the given series is an arithmetic progression. 1/2, 1/4, 1/5, 1/8

Answer 1

no it is not in AP becoz there common difference is not same

Answer 2

firstly, we have to calculate the common difference and if it same in all cases then it is AP.

case1
1/4-1/2= -1/2
case2
1/5-1/4= -1/20

so from the both cases it is clear that c.d. is different- different therefore it does not form any AP.