Answer: an = 4 × 5^(n - 1)
Step-by-step explanation:
The given sequence is a geometric sequence because consecutive terms differ by a common ratio. The
formula for determining the nth term of a geometric progression is expressed as
an = a1r^(n - 1)
Where
a1 represents the first term of the sequence.
r represents the common ratio.
n represents the number of terms.
From the information given,
a1 = 4
r = 20/4 = 100/20 = 5
Therefore, the explicit formula for the sequence is
an = 4 × 5^(n - 1)
