Question

What is the sum of the first five terms of a geometric series with a1 = 10 and r = 1/5?

Express your answer as an improper fraction in lowest terms without using spaces.

Answer 1

Anyone wanna help me w the rest of this quiz?

Answer 2

\[\Large \sum_{x=0}^nar^x=a\frac{1-r^{n+1}}{1-r} \]

Answer 3

I get what to put for, but what do I put for n?

Answer 4

Since you're interested in the first 5 terms..
you get
\(a+ar+ar^2+ar^3+ar^4\), so since it goes until \(ar^4\), n = 4

Answer 5

So far so good?