Question

the sum of the 1st and 17th terms of a Arithmetic sequence is 40 . the sum of its 1st and 18th term is 43 .what is the common difference​

Answer 1

first term=a

17th term = a+16d

total sum=40

a+a+16d=40

2a+16d=40

on simplifying

a+8d=20. eq-1

now

a+a+17d=43

2a+17d=43 eq-2

solving both equations

d=3

hence common diff is 3