Grade 10 Mathematics
Grade 10 · Term 4Mathematics

Number Patterns

We investigate number sequences where consecutive terms differ by the same constant amount (linear patterns). We find the general term of such a sequence and use it to calculate any term or find the position of a given value.

Week 3

12.1 Linear Number Patterns

  • Investigate number patterns with a constant difference between consecutive terms
  • Determine the general term of a linear pattern (without using a formula — derive it from first principles)
  • Use the general term to calculate specific terms and find the position of a given term
🌍

Real-World Connection

A taxi charges R8 per kilometre. After 1 km: R8; after 2 km: R16; after 3 km: R24. The differences are all R8 — this is a linear pattern. The general term T_n = 8n lets you instantly calculate the fare for any distance without listing all the values.

Definition

Constant Difference (Linear Pattern)

A number sequence has a constant (first) difference if each term is obtained by adding the same fixed value d to the previous term. The sequence increases if d > 0 and decreases if d < 0.

T2T1=T3T2=T4T3=d(constant)T_2 - T_1 = T_3 - T_2 = T_4 - T_3 = d\quad(\text{constant})

Property / Rule

General Term of a Linear Pattern

For a linear pattern with first term T₁ and constant difference d, the general term (n-th term) is derived by observing how each term is built from T₁ and d. The pattern adds d exactly (n−1) times to reach the n-th term.

Tn=T1+(n1)dT_n = T_1 + (n-1)d

💡 Tip

Always verify your general term by testing it for n = 1, n = 2, and n = 3. The formula should reproduce the given terms exactly. When asked to find the POSITION of a term, set Tₙ = given value and solve for n — the answer must be a positive integer.

ℹ️ Note

The general term Tₙ = T₁ + (n−1)d can be simplified to Tₙ = an + b form (where a = d and b = T₁ − d). Both forms are correct. The ATP requires you to derive the formula rather than simply quote it.

Worked Examples

Worked Example

Find the general term from the pattern

Problem

Given: 5; 8; 11; 14; … Find the general term and use it to find T20T_{20}.

Worked Example

Find which term has a given value

Problem

For the pattern 7; 12; 17; 22; … — is 102 a term? If so, which term?

Worked Example

Decreasing linear pattern

Problem

A pattern begins: 50; 45; 40; 35; … Find the general term and determine which term is the first negative term.
Activity — 8 Questions

CAPS Cognitive Level Distribution

L1 · Knowledge2 Q
L2 · Routine Procedures2 Q
L3 · Complex Procedures2 Q
L4 · Problem Solving2 Q
1
L1 · Knowledge1 mark
State the constant difference for: 3; 7; 11; 15; …
2
L1 · Knowledge2 marks
Find the 5th and 6th terms of the pattern: 2; 9; 16; 23; …
3
L2 · Routine Procedures3 marks
Find the general term of: 4; 10; 16; 22; …
4
L2 · Routine Procedures3 marks
Use the general term Tn=5n3T_n = 5n - 3 to find T15T_{15} and the position of the term equal to 97.
5
L3 · Complex Procedures5 marks
A pattern has T3=17T_3 = 17 and T7=33T_7 = 33. Find the general term and T50T_{50}.
6
L3 · Complex Procedures4 marks
For the pattern 2;  3;  8;  13;  -2;\;3;\;8;\;13;\;\ldots, find the first term greater than 100.
7
L4 · Problem Solving5 marks
Sequence A: 3;  9;  15;  21;  3;\;9;\;15;\;21;\;\ldots and Sequence B: 5;  9;  13;  17;  21;  5;\;9;\;13;\;17;\;21;\;\ldots share the term 9. Find the NEXT value that appears in both sequences.
8
L4 · Problem Solving4 marks
Determine whether 500 is a term of the pattern: 3; 10; 17; 24; … Justify your answer.
Number Patterns Grade 10 Maths CAPS Notes & Examples | MathSciBuddy