Question

The ap consist of 29 terms . the sum of the three middle most terms is 198 and the sum of the last three terms is 276. find the ap

Answer 1

middle term is 14 ,15, 16
so 14/2 (a+13d) +15/2 (a+14d) +16/2 (a+15d) =198
last 3 terms= 27,28,29
so 27/2 (a+26d)+28/2 (a+27d) +29/2 (a+28d)=276
so middle term will be
22.5a + 316d= 198
so last term will be
429a+1098d=276
substitute both
u will find a and d then u will get the answer