# Thread: l want to know the arithmetic progression formulae

1. ## l want to know the arithmetic progression formulae

my name is kabir and I am studying XI science I want to formulae of arithmetic progression.

2. ## Re: l want to know the arithmetic progression formulae

\displaystyle \begin{align*} t_n = a + (n-1)d \end{align*} and \displaystyle \begin{align*} S_n = \frac{n}{2}[2a + (n-1)d] \end{align*} or \displaystyle \begin{align*} S_n = \frac{n}{2}( a + l ) \end{align*}.