(i) 1, 3, 6, 10, ..... (1 mark)
Sol. 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 terms is not constant.
∴ The sequence is not an A.P.
