This shows how to find the nth term for a cubic sequence.
4 15 44 103 204
1st diff 11 29 59 101
2nd diff 18 30 42
3rd diff 12 12 so 12/6=2 It is a
sequence
Do a
line 2 16 54 128 250
Take this away from the original sequence
2 -1 -10 -25 -46
This is a quadratic sequence
1st diff -3 -9 -15 -21
2nd diff -6 -6 -6 -6 -6/2=-3
Do a
line -3 -12 -27 -48
Take this away from the quadratic sequence 5 11 17 23. This is linear, the difference is 6 so it is a 6n-1 sequence and the complete rule is
