Find the sum of all the 11 terms of an AP whose middle most term is 30.

Question

Philoid · Accepted Answer

No of terms = 11 as it is even

Middle term will be i.e. 6^th term

Let the first term be a and common difference be d of an AP

As

a_n = a + (n - 1)d

a₆ = a + (6 - 1)d

30 = a + 5d [ eqn 1]

Now as we know,

[ using eqn 1]