Answer:
a(n) = 5*2^(n-1)
Step-by-step explanation:
The nth term of a geometric series is given by the relation :
a(n) = ar^(n-1)
Where, a = first term ; r = common ratio ; a(n) = nth term of the series.
Given the series : 5, 10, 20, 40,
First term, a = 5
Common ratio = a2/ a1 = a3/a2
Common ratio = 10/5 = 20/10
Common ratio = 2 = 2
Hence, nth term =
a(n) = 5*2^(n-1)
