Question

What is the 18th term of the geometric series?
-2,10,-50,...

Answer 1

a term in a geometric series is

\[a_{n} = a \times r^{n - 1}\]

you know a = -2, n = 18

what is the value of r..?

when you get it substitute all values in the formula above to find the 18th term.

Answer 2

You should really memorize that formula.

Answer 3

So it's -2x(-5)^17 ?

Answer 4

Yes, you can simplify it a little without writing a huge number too.

Answer 5

My calculator won't allow to the 17th power so what would the answer be ?