ASSIGNMENT 3 2025
UNIQUE NO. 721003
DUE DATE: 18 JULY 2025
,Mathematics for Intermediate II
QUESTION 1
1.1.1.1 First differences
Diagram Small Diff Black Diff Grey Diff White Diff
1 1 - 1 - 0 - 0 -
2 4 3 3 2 1 1 0 0
3 9 5 5 2 3 2 1 1
4 16 7 7 2 6 3 3 2
5 25 9 9 2 10 4 6 3
6 36 11 11 2 10 4
1.1.1.2 Classification
Small: Quadratic (second differences constant)
Black: Linear (first differences constant)
Grey: Quadratic (second differences constant)
White: Quadratic (second differences constant)
1.1.1.3 Mathematical Justification
Black triangles: Constant first difference (2) → linear: Tn = 2n - 1
Small triangles: First differences not constant, but second differences constant
→ quadratic: Tn = n^2
1.1.2.1 Pattern Growth Description
Grey triangles: Increases as triangular numbers: +1, +2, +3, +4...
White triangles: Grows by 0, 1, 2, 3, 4... same as grey but delayed by one step
1.1.2.2 Flow Diagrams
, Grey Triangles: Tn = n(n - 1)/2
Input n → Multiply by (n - 1) → Divide by 2 → Output
White Triangles: Tn = (n - 1)(n - 2)/2
Input n → Subtract 1 → Multiply by (n - 2) → Divide by 2 → Output
1.1.3.1 Rule for Black Triangles
Pattern: 1, 3, 5, 7, 9, 11...
Tn = 2n - 1
Teaching: Show each added triangle is 2 more than previous. Use number line or
count-on strategy.
1.1.3.2 Rule for Grey Triangles
Tn = n(n - 1)/2
Misconception: Learners may think growth is additive instead of multiplicative.
Remedy: Use dot-pattern models to visualize triangular numbers.
1.1.3.3 Rule for White Triangles
Tn = (n - 1)(n - 2)/2
Proof: Grey at n - 1 = (n - 1)(n - 2)/2 = White at n Hence, proven.
1.1.4.1 Graph
Plot (1-5) for:
o Small: y = n^2
o Black: y = 2n - 1
o Grey: y = n(n - 1)/2
Label axes: x = diagram number, y = number of triangles