Find the sum of the given finite geometric series

Question

Find the sum of the given finite geometric series.

5+5/2+5/4+5/8+...+5/128

The sum of the finite geometric series is _____

(type and integer or a simplified fraction)

Answer 1

Given series , 5+5/2+5/4+5/8+...+5/128 = 5 + 5(1/2) + f(1/2)²+...+5(1/2)⁷

=5[1- (1/2)⁸]/[1 -(1/2)] ... using a+ar +ar²+ar³+...+ar^n-1= a (1-rⁿ)/(1-r)

=5(255/128) = 1275/128 or 9+123/128