Answer
$20,10,5, \dfrac{5}{2},\dfrac{5}{4}$
Work Step by Step
The general formula to find the nth term of a Geometric sequence is given as: $ a_{n+1}=a_nr $
We are given that $ a_1=20$
$ a_2=a_1r = (20)(\dfrac{1}{2})=10 ;\\ a_3=a_2r = (10)(\dfrac{1}{2})=5; \\ a_4=a_3r = (5)(\dfrac{1}{2})=\dfrac{5}{2} ; \\ a_5=a_4r = (\dfrac{5}{2})(\dfrac{1}{2})=\dfrac{5}{4}$
Hence, the first five terms are: $20,10,5, \dfrac{5}{2},\dfrac{5}{4}$
