Let a_1, a_2, …, a_n be in A.P. If a_5=2a_7 and a_ 11 = 18, then 12 ( 1 a_ 10 + a_ 11 + 1 a_ 11 + a_ 12 + + 1...

Question

Let a_1, a_2, …, a_n be in A.P. If a_5=2a_7 and a_ 11 = 18, then 12 ( 1 a_ 10 + a_ 11 + 1 a_ 11 + a_ 12 + + 1 a_ 17 + a_ 18 ) is equal to________.

Accepted Answer

8

JEE Main 2023 Mathematics question