Question

The first five terms of a pattern are
5
,
25
,
125
,
625
,
3125
. The equation
S
n
=
a
(
b
)
n
can be used to calculate the value,
S
n
, of any term in the pattern, where
n
is the term number.



What are the values of
a
and
b
in the equation?



A.
a
=
1
,
b
=
5

B.
a
=
5
,
b
=
5

C.
a
=
1
,
b
=
25

D.
a
=
5
,
b
=
25

Answer 1

Sequence is 5, 25, 125, ... = 5^1, 5^2, 5^3, ... so S_n = 5^n = 1*(5)^n. Thus a = 1, b = 5. (Choice A)