Algebra questions in CIE 0580 are predictable — but small mistakes can cost full marks. Use this checklist to fix the most common errors before your next exam.
1) Sign errors when expanding brackets
Fix: Write one line for each term, then combine like terms. Tip: Double-check negative signs by substituting a simple value (e.g., $x = 1$).
2) Factorising misses a common factor
Fix: Always take out the greatest common factor first. Example: $6x^2 + 9x = 3x(2x + 3)$.
3) Solving linear equations too early
Fix: Simplify both sides before moving terms. This reduces errors when you have fractions or brackets.
4) Mixing up “equation” and “expression”
Fix: Only solve when there is an equals sign. Otherwise, you simplify or factorise.
5) Incorrect substitution into formulas
Fix: Replace variables with brackets before you calculate. Example: $y = 2x + 3$ with $x = -4$ → $y = 2(-4) + 3$.
6) Cancelling terms incorrectly
Fix: You can cancel factors, not terms. Example: $x + 2$ cannot cancel with $x$.
7) Ignoring domain restrictions
Fix: Check if the question asks for valid values or restrictions. For example, a denominator of $x - 3$ means $x \neq 3$.
Quick Self-Check
Before you submit any algebra answer, run through this:
| Check | What to look for |
|---|---|
| Signs | Did I expand negatives correctly? |
| Common factor | Did I take out the greatest common factor? |
| Brackets | Did I use brackets when substituting? |
| Equation vs expression | Am I solving or simplifying? |
| Final answer | Did I answer what was asked? |
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