Question

What is the equation you use to solve arithmetic series?

and to find a certain number of terms?

thanks :)

Answer 1

\[\large a_n = a_1 + (n - 1 ) d\]
a_n = number of terms
a_1 = first term
d = difference between terms

Answer 2

For the sum
\[\large S_n = \frac{ n(a_1+a_n) }{ 2 }\]

Answer 3

okay, thank you!! :D