AlgebraIntroduction

What is Substitution?

Part of Simplifying Expressions · GCSE GCSE Mathematics revision

This introduction covers What is Substitution? within Simplifying Expressions for GCSE Mathematics. Revise Simplifying Expressions in Algebra for GCSE Mathematics with 11 exam-style questions and 5 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 8 of 19 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 8 of 19

Practice

11 questions

Recall

5 flashcards

What is Substitution?

Think of a formula like a recipe. If a cake recipe says "2 × eggs + 100g flour", you substitute in the actual number of eggs to work out how much flour! Substitution in maths is the same - you replace the letters (variables) with actual numbers to calculate an answer.

Keep building this topic

Read this section alongside the surrounding pages in Simplifying Expressions. That gives you the full topic sequence instead of a single isolated revision point.

Common Mistakes to Avoid Method: How to Substitute What Does "Simplify" Mean?What Are "Like Terms"?

Practice Questions for Simplifying Expressions

Which two terms are like terms?

A. 3x and 3y
B. 2x² and 5x
C. 4ab and 7ba
D. 6 and 6x

1 markfoundation

Explain why 3x + 2x² cannot be simplified to 5x³.

2 markshigher

Quick Recall Flashcards

Substitution

Replace each letter with its given value, then calculate

Like Terms

Terms with same letter and power: 2x and 5x are like terms

11 questions on Simplifying Expressions — practise free

Instant marking, adaptive difficulty, and 5 spaced repetition flashcards. Free until your GCSEs.

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Common Mistakes to Avoid

Method: How to Substitute