State whether the following sequence is an A.P. or not: 1, 3, 6, 10, ………

Ans.

Here, t1 = 1, t2 =3, t3 =6, t4 = 10

∴ t2 – t1 = 3 – 1 = 2

∴ t3 – t2 = 6 – 3 = 3

∴ t4 – t3 = 10 – 6 = 4

Here, the difference between any two   consecutive term is not constant

∴ it is not an A.P.