Mathematics for IGCSE & O level - Sequences (Section 2 - No. 5)

Identify the sequences that are quadratic sequences.

1, 4, 9, 16, 25...

1, 8, 27, 64...

2, 6, 12, 20, 30...

3, 7, 11, 15, 19...

Quadratic sequences have a second difference which is constant. Cubic sequences have a third constant difference.