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PATTERNS

Exam Cog
①LINEAR PATTERNS

Constant first difference = linear

y = mx + c

m = difference, c = start value

②THE nth TERM

Tn = the rule; put in position n

2,4,6,... → Tn = 2n

③SPOTTING QUADRATIC

1st differences constant → linear

2nd differences constant → quadratic

★ Same “gap of the gap” = quadratic
④FINDING Tn = an²+bn+c
  1. a = (2nd difference) ÷ 2
  2. Sub two terms in
  3. Solve for b and c
  4. Verify with a third term
⑤GRAPHS

Linear pattern → straight line

Quadratic pattern → curve (parabola)

⑥WATCH-OUTS
⚠ Check whether the terms start at T0 or T1 before substituting.