Question

A sequence is given by `5, 15, 25, 35, ...` Which term of the series is `145`?

Answer 1

The `n^(th)` term would be given by the expression `10(n-1)+5`.

Explanation:

I have to admit that I really did this by inspection. Showing that it works:

`n=1` yields `10(1-1)+5=5`

`n=2` yields `10(2-1)+5=15`

And so on.

`145` is the `15^(th)` term:

`n=15` yields `10(15-1)+5=145`