Find the sum of two middle terms of the AP `-4/3,-1,-2/3,-1/3,...,4(1/3)`

Answer

3

Explanation

`a = (-4)/(3), d = (-1 + (4)/(3)) = (1)/(3) "and " T_(n) = (13)/(3)`.
`therefore T_(n) = (13)/(3) rArr a +(n-1)d = (13)/(3) rArr (-4)/(3) + (n-1) xx (1)/(3) = (13)/(3) rArr n = 18`
`therefore` sum of two middle most terms
` = (T_(9) + T_(10)) = (a+8d) + (a+9d) = (2a + 17d) = ((-8)/(3) + (17)/(3)) = (9)/(3) = 3.`