Answer:
324
Step-by-step explanation:
a
2
a
1
=
12
4
=
3
a
3
a
2
=
36
12
=
3
⇒
common ratio
=
r
=
3
and first term
=
a
1
=
4
no: of terms
=
n
=
9
Sum of geometric series is given by
S
u
m
=
a
1
(
1
−
r
n
)
1
−
r
⇒
S
u
m
=
4
(
1
−
3
9
)
1
−
3
=
4
(
1
−
19683
)
−
2
=
−
2
(
−
19682
)
=
324
