AlgebraExam Tips
Substitution: Common Mistakes to Avoid
Part of Simplifying Expressions — GCSE Mathematics
This exam tips covers Substitution: Common Mistakes to Avoid within Simplifying Expressions for GCSE Mathematics. Revise Simplifying Expressions in Algebra for GCSE Mathematics with 11 exam-style questions and 5 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 14 of 18 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 14 of 18
Practice
11 questions
Recall
5 flashcards
Substitution: Common Mistakes to Avoid
✗ (−3)² = −9
✓ (−3)² = (−3)×(−3) = 9
Negative × negative = positive!
✗ 2x² when x=3 gives 6² = 36
✓ 2(3²) = 2(9) = 18
Square the x first, then multiply by 2
✗ Forgetting BIDMAS
✓ Do powers before multiplication
x² + 3x: do x² first, then 3x, then add
✗ −3² = 9
✓ −3² = −(3²) = −9
Without brackets, the minus stays separate