Evaluate the sum of the following finite geometric series. 5 + 10 + 20 + 40 +...+320. Sn = ___

Answer 1

The formula used for this is S_n = a₁ x (1-rⁿ)/(1-r)

After substituting, you get S₇ = 5 x (1-2^7)/(1-2)

S₇= 5 x 127

S₇ = 635

The sum of this series is 635.

Answer 2

320 = 5(2)^n-1

64 = 2^n-1

2⁶ = 2^n-1

6 = n -1

7 = n

S₇ = 5(2⁷ - 1) / (2 - 1)

Can you calculate and answer?