Need to Know
Patterns
The rules you must have ready for the exam.
How to use this: say each rule in your head, then tap Show me to check.
Linear
1 ruleRule 01
From a table
Constant first difference → linear. Rule y = mx + c (m = difference, c = start).
Sequences
1 ruleRule 02
The nth term
Tn is the rule. Put in the position n to get any term.
Spotting a quadratic
1 ruleRule 03
Second differences
First differences constant → linear. Second differences constant → quadratic (Tn = an²+bn+c).
Finding the rule
1 ruleRule 04
a, then b and c
a = (second difference)/2. Then sub two terms in and solve for b and c.
Mathslive.ie · Patterns · Need to Know