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Substitution replaces the letters in an expression or formula with given numbers and evaluates the result, taking care with order of operations, negatives and powers. It's a core topic in GCSE and iGCSE Maths with Edexcel and the other major boards. This free interactive course teaches the method with worked examples and gives instant-feedback practice questions to lock it in.
How you do it
Replace each letter with its value in brackets, then evaluate using the order of operations. The brackets matter with negatives — minus 3 squared is 9, but the negative of 3 squared is minus 9.
Before you start
It assumes you can handle algebraic notation and order of operations. Foundation and Higher tier students all cover it. Keep it sharp for formulae, sequences and graphs. Filed under Algebra.
What you learn
Substitution means replacing the letters in an expression or formula with given numbers, then working out the value. Follow the order of operations (powers and brackets before multiply/divide, and those before add/subtract). To substitute, replace each letter with its number and then calculate. A formula is just an expression with a subject. The course works through substituting into expressions, powers and negatives and substituting into formulae. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
In our GCSE maths courses, Substitution belongs to Algebra and is met in Foundation tier. There are 3 teaching sections and 2 fully worked examples, plus 3 sets of check questions. It sits alongside Algebraic Fractions, Algebraic Notation, Algebraic Proof, Completing the Square and Differentiation in the same strand. The Algebra revision engine gives you as many extra questions as you want, tracked on your skill tree.
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