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Changing the subject

Free Printable Changing the subject PDF Worksheets, Revision Guide & GCSE Past Paper Questions (Grade 5)

Download free changing the subject worksheets (PDF), GCSE maths past paper questions and worked solutions for Changing the subject (5F). This is a Grade 5 algebra topic from the GCSE questions by topic collection for Foundation and Higher tier crossover GCSE Maths (Edexcel, AQA, OCR and IGCSE).

The free PDF worksheets table below brings together printable question booklets (Qs) and worked answers or mark schemes (Ans) from IGCSE MT, Maths Genie, Maths4Everyone, Corbett Maths, Maths Made Easy, Dr Frost, Naiker Maths, Dr Austin, Metatutor, GCSE Maths Rocket, E Classroom and PMT, along with past paper question booklets.

Below the worksheet links you can read our changing the subject revision notes and worked examples with diagrams, try real GCSE past paper changing the subject questions with step-by-step solutions, or download a PDF of all changing the subject worksheet links.

Free Changing the subject PDF Worksheets & Answers

Grade 5 • Topic 5F
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GCSE Maths Grade 5 Revision Notes & Method

Guide to Changing the subject: Explanation, Diagrams & Worked Examples

Download Printable One Page Guide (PDF)

Explanation:

To change the subject of a formula, use inverse operations step by step to isolate the target letter on one side of the equals sign (multiply out fractions first, expand brackets, and undo powers with roots or vice versa).

If the letter you want appears twice in the formula, expand any brackets, collect all terms containing the target letter on one side and all other terms on the opposite side, then factorise out the target letter before dividing.

Example 1: Make v the subject of E = 12mv2.

Solution:

Multiply both sides by 2: 2E = mv2
Divide both sides by m: 2Em = v2
Square root both sides to isolate v:
Answer: v = ±√(2Em)

Example 2: Make x the subject of y = 3x + 2x − 4.

Solution:

Multiply by (x − 4): y(x − 4) = 3x + 2 → xy − 4y = 3x + 2
Collect x terms on left: xy − 3x = 4y + 2
Factorise out x: x(y − 3) = 4y + 2
Answer: x = 4y + 2y − 3
Scanned GCSE Exam Questions & Worked Solutions

GCSE Past Paper Changing the subject Questions & Answers

Past Paper Example 1 IGCSE Jan 2023 1F Q13 4 marks
p = t - ac
t = 18   a = -3   c = 5
(a) Work out the value of p [2 marks]
(b) Make x the subject of the formula d = 3x + 10 [2 marks]
Worked Solution & Mark Scheme (4 marks)
Part (a) Solution:
p = 18 − (−3)(5) = 18 − (−15) = 33 M1 A1
Answer (a): p = 33
Part (b) Solution:
d − 10 = 3x M1
⇒ x = (d − 10)/3 A1
Answer (b): x = x = d - 103
Past Paper Example 2 IGCSE Jun 2025 2F Q12 5 marks
(a) Make y the subject of w = 3y – d. (2) (b) Diego buys b boxes (12 crayons each) and p packets (3 crayons each) for a total of T crayons. Write down a formula for T in terms of b and p. (3)
(a) Make y the subject of w = 3y - d [2 marks]
(b) Write down a formula for T in terms of b and p [3 marks]
Worked Solution & Mark Scheme (5 marks)
Part (a) Solution:
w + d = 3y M1
⇒ y = (w + d)/3 A1
Answer (a): y = y = w + d3
Part (b) Solution:
Use + for more/older, - for less/fewer/younger, and multiply/divide for rates. M1
e.g. 4 less than m is m - 4 M1
3 times m is 3m
Answer: T = 12b + 3p A1
Answer (b): T = T = 12b + 3p
Past Paper Example 3 IGCSE Nov 2020 2F Q14 5 marks
(a) Factorise 25f − 10 (1) (b) Make y subject of c = 5y − h (2) (c) Solve 4x + 7 > 2 (2)
(a) Factorise 25f - 10 [1 mark]
(b) Make y the subject of the formula c = 5y - h [2 marks]
(c) Solve the inequality 4x + 7 > 2 [2 marks]
Worked Solution & Mark Scheme (5 marks)
Part (a) Solution:
5(5f − 2)
Answer (a): 5(5f - 2)
Part (b) Solution:
c + h = 5y M1
⇒ y = (c + h) / 5 A1
Answer (b): y = y = c + h5
Part (c) Solution:
4x > −5 M1
⇒ x > −1.25 A1
Answer (c): x > -1.25

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