AlgebraExam Tips

Common Mistakes to Avoid

Part of Simplifying Expressions · GCSE GCSE Mathematics revision

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.

Topic position

Section 7 of 19

Practice

11 questions

Recall

5 flashcards

Common Mistakes to Avoid

✗ 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

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.

Worked Example 3: With Powers What is Substitution?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

Like Terms

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

Substitution

Replace each letter with its given value, then calculate

11 questions on Simplifying Expressions — practise free

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Worked Example 3: With Powers

What is Substitution?