Obtain the sum of the first 56 terms of an A.P.  Whose 18th and 39th terms are 52 a
Channel: Doubtnut
Date: 2020-03-29

Obtain the sum of the first 56 terms of an A.P.  Whose 18th and 39th terms are 52 and 148 respectively  (1) Usint `t_(18)` and `t_(39)` find two simultaneous equations in variables a and d.  (2) Using  these equations, find `S_(56)`