✗ 3x + 2y = 5xy
✓ 3x + 2y (can't simplify)
Unlike terms stay separate
✗ 2x + 3x² = 5x³
✓ 2x + 3x² (can't simplify)
Different powers = unlike terms
✗ 5x − 3x = 2
✓ 5x − 3x = 2x
Keep the variable after combining
✗ −x² + 3x² = 2x²
✓ −x² + 3x² = 2x²
This one is correct! Watch signs carefully
✗ Forgetting −x means −1x
✓ 5x − x = 5x − 1x = 4x
Invisible coefficient is 1
This exam tips covers 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. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 7 of 19 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Practice questions for Simplifying Expressions
Which two terms are like terms?
Explain why 3x + 2x² cannot be simplified to 5x³.
Quick recall flashcards
Like Terms
Terms with same letter and power: 2x and 5x are like terms
Substitution
Replace each letter with its given value, then calculate