Algebra

Expanding & Factorising Linear Expressions

1

Match Expression to Expanded Form

Draw a line to match each expression to its expanded form.

2(x + 3)
3(2y − 4)
−(a + 5)
4(3m + 2)
5(x − 1)
5x − 5
12m + 8
−a − 5
6y − 12
2x + 6
2

Expand the Brackets

Circle the correct expanded form.

3(x + 4)

3x + 12
3x + 4
x + 12

5(2y − 3)

10y − 15
10y − 3
7y − 8

−2(a − 6)

−2a + 12
−2a − 12
2a − 12

4(3n + 1)

12n + 4
12n + 1
7n + 4
3

Match to Factorised Form

Draw a line to match each expression to its factorised form.

6x + 9
4y − 12
10a + 15
8m − 6
12n + 18
2(4m − 3)
6(2n + 3)
3(2x + 3)
5(2a + 3)
4(y − 3)
4

Factorise the Expression

Circle the correct factorised form.

8x + 12

4(2x + 3)
8(x + 4)
2(4x + 6)

15y − 10

5(3y − 2)
5(y − 2)
15(y − 1)

6a + 9b

3(2a + 3b)
6(a + b)
3(2a + 9b)

14m − 21

7(2m − 3)
7(m − 3)
14(m − 3)
5

Expand and Simplify

Expand then collect like terms.

2(x + 3) + 3(x + 1)

5x + 9
5x + 4
6x + 9

4(y − 2) − 2(y + 1)

2y − 10
2y − 6
6y − 10

3(2a + 1) + 2(a − 3)

8a − 3
8a + 3
6a − 3
6

Fully Simplified or Not?

Sort: which expressions are already fully simplified?

3x + 5x
4a + 3b
2y − y + 4
6m + 3
5n − 2n + n
x² + 2x
Fully simplified
Can simplify further
7

Algebra in Context

Write and simplify expressions.

A rectangle has length (3x + 2) and width 4. Write and expand an expression for its perimeter.

Factorise fully: 12x² + 18x. Show the HCF and your working.

8

Expanding with Negative Coefficients

Expand each expression carefully — watch the sign of every term.

−3(x + 5)

−3x − 15
−3x + 15
3x + 15

−2(4a − 3)

−8a + 6
−8a − 6
8a − 6

−(6n − 1)

−6n + 1
−6n − 1
6n + 1

5(−2y + 3)

−10y + 15
10y − 15
−10y − 15
9

Factorising with Negative HCF

Factorise, taking out a negative HCF where shown.

−4x − 12

−4(x + 3)
4(−x − 3)
−4(x − 3)

−6a + 9

−3(2a − 3)
3(−2a + 3)
−3(2a + 3)

−10m − 15

−5(2m + 3)
5(2m + 3)
−5(2m − 3)
10

Substituting into Expanded Expressions

Substitute the given value and evaluate.

3(x + 4) when x = 2

18
14
24

−2(a − 5) when a = 1

8
−8
12

4(2n + 1) when n = −1

−4
4
12

5(y − 3) when y = 3

0
15
−15
11

Perimeter and Area with Brackets

Write an expression with brackets, then expand it. Show all working.

A room has length (2x + 5) m and width 3 m. Write an expression for the perimeter using brackets, then expand it.

A border of tiles is placed around a rectangular garden that is x m by 4 m. The border adds 1 m on each side. Write an expression for the border area using brackets and expand it.

12

Expanding or Factorising?

Sort each task: are you expanding (removing brackets) or factorising (adding brackets)?

6x + 9 → 3(2x + 3)
4(x − 2) → 4x − 8
10y − 15 → 5(2y − 3)
−2(a + 7) → −2a − 14
8m + 12 → 4(2m + 3)
3(4n − 1) → 12n − 3
Expanding
Factorising
13

Algebra in Architecture

Explore how algebra describes real measurements.

  • 1Measure the length and width of a room in your home. If one dimension is expressed as (2x + 1) metres, find the value of x. Calculate the perimeter using the expression and check against direct measurement.
  • 2Design a rectangular garden where one side is 3 m longer than twice the other side. Write an expression for the perimeter. If the shorter side is 4 m, what is the perimeter?
  • 3Look at a product in a supermarket with a price of $(3n + 50) cents. What value of n makes this equal to $2.00? Factorise the expression.
17

Three-Term Expansion

Expand the bracket — it has three terms inside.

2(x + y + 3)

2x + 2y + 6
2x + y + 3
2x + 2y + 3

3(a − 2b + 4)

3a − 6b + 12
3a − 2b + 4
3a − 6b + 4

−4(2m + n − 1)

−8m − 4n + 4
−8m + n − 1
−8m − 4n − 4

5(x + 2y − z)

5x + 10y − 5z
5x + 2y − z
5x + 10y − z
20

Find the HCF — Sort by Value

Identify the correct HCF for each expression and sort from smallest to largest HCF.

4x + 10 → HCF = 2
9y − 15 → HCF = 3
15a + 25 → HCF = 5
12m + 18 → HCF = 6
HCF = 2
HCF = 3
HCF = 5
HCF = 6
21

Expand and Simplify — Two Brackets

Expand both brackets, then collect like terms.

3(x + 2) + 2(x + 5)

5x + 16
5x + 7
6x + 16

4(y − 1) − 2(y + 3)

2y − 10
2y − 4
6y − 10

5(2a + 1) − 3(a − 2)

7a + 11
7a − 1
10a + 11

2(3m − 4) + 3(m + 2)

9m − 2
9m + 2
6m − 2
22

Collect Like Terms After Expanding

Expand and fully simplify each expression. Show all working.

Simplify: 4(2x + 3) − 2(x − 1)

Simplify: 3(a + b) + 2(2a − 3b)

Simplify: 5(y + 4) − 3(y + 6) + 2(y − 1)

26

Algebraic Word Problems

Write an algebraic expression with brackets, then expand. Show all working.

A rectangle has length (3x + 4) cm and width 5 cm. Write and expand an expression for its perimeter.

A square has side length (2m − 1) cm. Write an expression for its area and expand it.

Three friends each have (n + 7) dollars. Write and simplify an expression for their total money.

28

Which Factorisation is Complete?

Circle the fully factorised form.

12x + 18:

6(2x + 3)
2(6x + 9)
3(4x + 6)

8y − 12:

4(2y − 3)
2(4y − 6)
8(y − 1.5)

15a + 10b:

5(3a + 2b)
5a(3 + 2b/a)
10(1.5a + b)

6x² + 9x:

3x(2x + 3)
3(2x² + 3x)
x(6x + 9)
29

Factorising — Challenging Problems

Factorise each expression completely. Show the HCF at each step.

Factorise: 24a²b − 16ab²

Factorise: 3x(y + 2) + 6(y + 2). (Hint: (y + 2) is a common factor.)

Factorise: x(x + 3) − 2(x + 3). Simplify fully.

TipFor the last problem, suggest your child try substituting a value to check their answer.
30

Sort by Factorisation Method

Sort each expression by what type of factorisation it requires.

6x + 9 → 3(2x + 3)
x² + 2x → x(x + 2)
4a² − 6a → 2a(2a − 3)
5m + 10 → 5(m + 2)
y³ − y² → y²(y − 1)
8 + 12n → 4(2 + 3n)
Common number factor only
Common variable factor only
Both number and variable factor
31

Expanding Brackets — Using Algebra to Solve

Expand and use the resulting expression to solve.

A rectangle has width w and length (w + 5). Its perimeter is 34 cm. Write and expand the perimeter expression, then solve for w.

Two rectangles: Rectangle A is 3(x + 2) cm² and Rectangle B is 2(x + 4) cm². They have equal areas. Solve for x.

33

Introduction to Expanding Two Brackets (FOIL)

Use FOIL (First, Outside, Inside, Last) to expand each product of two brackets.

Expand (x + 2)(x + 5). F = x × x = ___, O = x × 5 = ___, I = 2 × x = ___, L = 2 × 5 = ___. Collect like terms.

Expand (x + 3)(x − 4). Show full FOIL working and simplify.

Expand (2x + 1)(x + 3). Show full working.

TipFOIL is a mnemonic for the four products when expanding two binomials. This technique is a preview of Year 9 algebra — treat it as enrichment if it is unfamiliar.
36

Expanding with Negatives — Set A

Expand. Be careful with signs.

−3(x − 4)

−(2x + 5y − 1)

2(3x + 1) − (x − 5)

3(2x − y) + 2(x + 4y)

TipDistributing a negative sign flips all signs inside the brackets.
37

Factorising — Set A

Factorise fully by taking out the highest common factor (HCF).

6x + 9

12y² − 8y

5x² + 15x

−4a + 10b − 6

TipFind the HCF of coefficients and variables, then divide each term by it.
38

Verify by Expanding

Expand the factorised form to check if it equals the original.

Is 3(2x + 5) = 6x + 15?

Yes — expand to check
No — it equals 6x + 5
No — it equals 5x + 15

Is 4(x − 2) + 3 = 4x − 5?

Yes — 4x − 8 + 3 = 4x − 5
No — it equals 4x − 2
No — it equals 4x + 5

Is 2(3x + 4) − (x + 2) = 5x + 6?

Yes — 6x + 8 − x − 2 = 5x + 6
No — it equals 5x + 10
No — it equals 7x + 6
40

Expanding — Set B

Expand and collect like terms.

3(2x + 5) + 4(x − 1)

2(3y − 4) − 3(y + 2)

x(x + 3) + 2(x² − 1)

5(2a − b) − (a + 3b)

41

Factorising — Set B

Factorise fully.

14x² − 21xy

8a²b + 12ab²

15p³ − 25p²q + 10pq

−6x² + 9x

TipCheck your answer by expanding — you should get back to the original expression.
42

Expand or Factorise?

Sort each task: does it require expanding or factorising?

Write 12x + 18 as a product
Simplify 4(x + 3)
Write 3x(2 − x) without brackets
Write 6y² − 9y as a product using HCF
Simplify −2(3a − b) + a
Rewrite 5ab + 10b² using HCF
Expanding (multiply out brackets)
Factorising (take out common factor)
43

Algebra in Geometry

Use expanding or factorising to solve each geometry problem.

A rectangle has length (2x + 5) cm and width 3 cm. Write an expression for the area. Expand and simplify.

The perimeter of a square is (8x + 12) cm. Write an expression for the side length by factorising.

Two rectangles are placed side by side. One has dimensions 4 × x and the other has dimensions 4 × 3. Write the total area by factorising.

TipSetting up algebraic expressions for areas and perimeters develops cross-strand thinking.
45

Solving Equations by Expanding First

Expand brackets, then solve the equation.

3(x + 4) = 21. Expand, then solve.

2(3x − 1) = 4(x + 3). Expand both sides, then solve.

5(2x + 1) − 3(x − 2) = 28. Expand, simplify, then solve.

TipMany linear equations require expanding before you can isolate the variable.
47

Algebraic Expressions — Word Problems

Write and simplify an algebraic expression for each problem.

A box contains n chocolates. Alice takes 3 handfuls of n chocolates and Bob takes 2 handfuls of (n − 4). Write and simplify an expression for the total taken.

The cost of a party venue is $50 per person for adults and $30 per person for children. There are a adults and c children. Write an expression for the total cost. If 8 adults and 12 children attend, find the total.

TipEncourage setting up the expression before simplifying — the setup is often the hardest part.
48

Factorising to Simplify

Factorise the numerator and cancel common factors to simplify each fraction.

Simplify (6x² + 9x) ÷ 3x

Simplify (12y − 8) ÷ 4

Simplify (10a²b + 15ab²) ÷ 5ab

TipThis connects factorising to algebraic fractions — a key skill for Year 9.
49

Error Analysis

Find and fix the errors.

Student: '−2(x − 3) = −2x − 6.' What is wrong? Write the correct expansion.

Student: 'The HCF of 8x² and 12x is 4, so 8x² + 12x = 4(2x² + 3x).' Is this fully factorised? How could it be improved?

TipNoticing errors in algebra is as valuable as solving correctly.
50

Creating Equivalent Expressions

For each expression, write two equivalent forms: one expanded and one factorised.

Start with 3x(4 − 2x). Expanded form? Factorised form?

Start with 5y + 15. Factorised form? Check by expanding.

TipBeing able to move between forms fluently is a key algebraic skill.
51

Reflection: Expanding and Factorising

Summarise what you have learned.

Explain expanding in your own words with one example.

Explain factorising in your own words with one example.

When would you expand an expression? When would you factorise? Give a real example of each.

Draw here
TipWritten reflection consolidates understanding and prepares for assessment.