Question

In an A.P. 19th term is 52and 38th is 128,find the sum of firsr 56 terms​

Answer 1

Answer:

ATQ,

a+18d=52. (1)

a+37d=128. (2)

on solving (1) and (2)

we get a= -20 &d=4

sum of first 56 terms will be

56/2[2(-20)+(55)(4)]

504