Find the sum of 8 terms of a geometric progression whose 1st term is 8 and common ratio is 2.

Find the sum of 8 terms of a geometric progression whose 1st term is 8 and common ratio is 2. Correct Answer 2040

GIVEN:

1^st 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 ×

⇒ 8 ×

⇒ 8 × 255

⇒ 2040