Question

Find the sum of the infinite geometric series: 4+1+1/4+1/16+1/64

Answer 1

use
\[S=\frac{a}{1-r}\] with \(a=4,r=\frac{1}{4}\)

Answer 2

you can almost do it in your head
\(1-\frac{1}{4}=\frac{3}{4}\)
the reciprocal of \(\frac{3}{4}\) is \(\frac{4}{3}\)
multiply by 4 you get \(\frac{16}{3}\)