Question

What is the 30th term of the arithmetic series 11+16+21+26+...?

Answer 1

`T_30 = 11 + 145 =156`

Explanation:

It can easily be seen that the common difference between the terms is 5. The first term, a, is 11

The general term is `Tn = a + (n-1)d`
For this series is `T_n = 11 + (n-1)5`

So for`T_30 = 11 + 29 xx 5`

= `11 +145 = 156`