find the sum of the first 8 terms of GP whose first term a=1 and common ratio r= 2
Answers
Answered by
1
Answer:
Given, a
1
=2,r=2
S
n
=
r−1
a
1
(r
n
−1)
S
8
=
2−1
2(2
8
−1)
=
1
2(255)
=510
Step-by-step explanation:
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Answered by
3
Answer:
GIVEN:
1st term is 8 and common ratio is 2 of a geometric progression.
CONCEPT:
Geometric progression formulas for calculating the sum of ‘n’ terms.
FORMULA USED:
Sum of ‘n’ terms of a geometric progression:
⇒ a(rn - 1) / (r - 1) if r > 1
⇒ a(1 - rn) / (1 - r) if r < 1
Where
a = first term, r = common ratio, n = number of terms
CALCULATION:
r = 2 (r > 1)
Sum of 8 terms = a(r8 - 1) / (r - 1)
⇒ 8 × [(28 - 1) / (2 - 1)]
⇒ 8 × [256 - 1]
⇒ 8 × 255
⇒ 2040
∴ Sum of 8 terms of GP is 2040
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