Mathematics

Problem

If the sum of first 11 terms of an AP,

a_1, a_2, a_3, \dots

is 0 (

a_1 \neq 0

), then the sum of the AP,

a_1, a_3, a_5, \dots, a_{23}

ka_1

, where

k

is equal to (a)

-\frac{121}{10}

(b)

\frac{121}{10}

(c)

\frac{72}{5}

(d)

-\frac{72}{5}