Answer:
It is quadratic with nth term = n^2 + n.
Step-by-step explanation:
Number of squares in each term = 2, 6 and 12
Differences between these are 4 and 6
6 - 4 = 2
This is an indication of a quadratic function with n^2 the first term.
Value of n^2 for first 3 terms
= 1 4 9 and the terms are:
2 6 12
Differences 1 2 3
This last term = n
So the quadratic function for this sequence is
n^2 + n.