Question

Write the formula of the sum of first n terms for an A.P.

Answer 1

Sum of the first n terms is given by

S_n = `"n"/2[2"a" + ("n" - 1)"d"]`,

where a = first term,

d = common difference

OR

S_n = `"n"/2("t"_1 + "t"_"n")`,

where t₁ = first term,

t_n = last term