Find the sum of 3+3
2
+3
3
+⋯+3
8
.
- A9840
- B6561
- C6560
- D3280
Solution & Step-by-step Explanation
The given series is a Geometric Progression (GP):
First term (a) = 3
Common ratio (r) = 3
Number of terms (n) = 8
The formula for the sum of the first n terms of a GP is:
S
n
=
r−1
a(r
n
−1)
S
8
=
3−1
3(3
8
−1)
3
8
=(3
4
)
2
=81
2
=6561
S
8
=
2
3(6561−1)
=
2
3×6560
=3×3280=9840
First term (a) = 3
Common ratio (r) = 3
Number of terms (n) = 8
The formula for the sum of the first n terms of a GP is:
S
n
=
r−1
a(r
n
−1)
S
8
=
3−1
3(3
8
−1)
3
8
=(3
4
)
2
=81
2
=6561
S
8
=
2
3(6561−1)
=
2
3×6560
=3×3280=9840