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A Level Algebra
Proof
Learn proof as part of develop pure algebra, proof, functions, graphs, sequences, trigonometry, exponentials and vectors.
Key idea
Keep both sides balanced, use notation accurately, and check by substituting your answer back in.
What you will learn
Use proof meaning confidently.
Use proof representations confidently.
Use proof methods confidently.
Use proof applications confidently.
Success checklist
✓I can explain what proof means.
✓I can choose a suitable method without being told.
✓I can show clear working and check my answer.
Worked example
Solve 3𝑥 + 5 = 20.
Step 1
Subtract 5 from both sides: 3𝑥 = 15.
Step 2
Divide both sides by 3.
Step 3
𝑥 = 5.
Answer
𝑥 = 5
Quick practice
Question 1
Simplify 4𝑥 + 3𝑥 - 2𝑥.
Question 2
Solve 2𝑥 - 7 = 11.
Question 3
Expand 5(𝑥 + 3).
Related resources
These are linked to the wider Algebra topic for now.