Question

Write the formula for sum of 'n terms of A.P. whose first term is 'a', common difference d'​

Answer 1

$\huge\underline\mathfrak{Answer-}$

$S_n$ = $\dfrac{n}{2}(2a+(n-1)d)$

Here, $S_n$ refers to the sum of n terms.

n refers to the number of terms.

a refers to the first term.

d refers to the common difference between consecutive terms.

Similarly, there's a formula for finding last term :

$a_n$ = a + ( n - 1 )d

Answer 2

Formula is :

S n = n / 2 [ 2a+ ( n- 1 ) d]

I hope it help you