Question

define a.p series?with formules​

Answer 1

what is this a.p series. Is that Arithmetic progression!Then

an=a+(n_1)d
sn=n/2(an+a)
sn=n/2(2a+(n_1)d)
sn=n/2 (a+l)

Answer 2

An arithmetic progression is a sequence of numbers such that the difference of any two successive members is a constant.  

For example, the sequence 1, 2, 3, 4, ... is an arithmetic progression with common difference 1.