Question

evaluate the series 72+12+2+...

Answer 1

There is a formula for the sum of an infinite geometric series, which this is.
If a is the first term, and r is the common ration, then the sum to infinity is \[a/(1-r)\].

Answer 2

What is a?
And: What is r?

Answer 3

@alexgriffin

Answer 4

a= 72.
r = 1/6.
a/ (1-r) = 72/(1-5/6) = 72/(5/6) = 432/5.
Do you understand how I got that?