The difference between each number in the sequence is +3, +5, +7, +9 The difference between these is +2 every time. To find the nth term, you need to divide the second difference by 2 so 2/2=1. Then you write out the sequence of 1n^2 so in this case it is 1, 4, 9, 16, 25 Finally you need to find how you get from this sequence to the original sequence. In this case it it -6 each time. Therefore the nth term is n^2 -6
