IGCSE Math: Sequences Summary

1. Linear Sequences (Arithmetic)

Rule: Constant first difference.

Formula: dn + (a - d)

• d: Common difference
• a: First term

2. Quadratic Sequences

Rule: Constant second difference.

General Form: an² + bn + c

• Find 'a': Second difference ÷ 2

3. Quick Recognition List

Type	nth Term
Square Numbers	n2
Cube Numbers	n3
Powers of 2	2n

Note: Formal AP/GP formulas from A-Levels are NOT required for IGCSE 0580. Focus on finding the nth term logic!