Question

4th term 2 ,7th term 3 find common difference in this arithmetic sequence

Answer 1

Answer:

Solving the above two equations we get,

a = 6

d = 4

Sum of n terms (Sn) is given by

Sn = (n/2)*(2*a + (n-1)*d)

=(n/2)*(12 + (n-1)*4)

= n*(6 + 2*n -2)

= 2*n*( n + 2 )