What is the sum of an 8-term geometric series if the first term is - 11, the last term is 859,375, and the common ratio is - 5? - 143,231 - 36,047 144,177 716,144

The sum of geometric series is 716144

Step-by-step explanation:

Given

First term=a_1 = - 11

Last term=a_8=859375

Common ration of geometric series=r = - 5

And

Total terms in geometric sequence=n=8

We know that the formula for sum of geometric series is:

S_n = (a_1 (1-r^n)) / (1-r)

= (-11 (1 - (-5) ^8) / (1 - (-5))

= (-11 (1-5^8)) / (1+5)

= (-11 (1-390625)) / 6

= (-11 (-390624))) / 6

=4296864/6

=716144

So the sum of geometric series is: 716144 ...