Question

octant the sum of the first 56 terms of an ap who 19th and 38th term are 52 and 148 respectively​

Answer 1

Answer:

a+18d=52

so 52-18d=a ----eq1

now a+37d=148

so a=148-37d------eq2

d=96/17

a=-844/17

so s56=n/2(2a+(n-1)d=11508