Question

What is the sum of an 8-term geometric sequence if the first term is 10 and the last term is
781,250?

Answer 1

the formula is:
\[first\frac{1-r^n}{1-r}\]

Answer 2

first you need to find value of common ratio r
r^7 = 782, 250 / 10 = 78250

Answer 3

\[Sum = \frac{a(r^n - 1)}{(r-1)}\]

Answer 4

\[r^7 = 78125\]

Find r..

Answer 5

r = 5

Answer 6

given that\[a_n=a_1*r^{(n-1)}\]
\[\left(\frac{a_n}{a_1}\right)^{\frac{1}{n-1}}=r\]

that was tough to type in lol

Answer 7

i Got 976,560

Answer 8

is that right?

Answer 9

\[Sum = \frac{10((5)^8 - 1)}{(5-1)}\]

Answer 10

Well Done..

Answer 11

You are right..

Answer 12

thank you! all Of You!

Answer 13

Welcome dear.