Question

the sequence is 1,3,6,10,15.....
give the formula for rth term

Answer 1

rth?

Answer 2

Ask yourself: Is this an arithmetic sequence or a geometric sequence?

Answer 3

Answer on paper or here on OpenStudy:

How do we get the 2nd term from the first?
the 3rd from the second?
the 4th from the third?

You should see a pattern emerging.

Answer 4

none of AP or GPbut the common differnce rises as 2,3,4,5 .....