Question

If {an) is an arithmetic sequence where a1=-23 and the common difference is 6, find a79

Answer 1

Given:

The first term

$a_1=-23$

The common difference, d=6

To find

$a_{79}$

Using the nth term formula,

$\begin{gathered} a_n=a+(n-1)d \\ a_{79}=-23+(79-1)6 \\ =-23+(78)6 \\ =-23+468 \\ =445 \end{gathered}$

Hence, the answer is,

$a_n=445$