Edexcel International A-Level Mathematics: Frequent mistakes

Pearson Edexcel International A-level Mathematics shares common error patterns with other boards. Principal Examiner Feedback emphasises showing working, correct notation and question reading.

Showing working

Unsupported answers

Candidates frequently fail to show sufficient working. Calculator-only answers score zero if wrong. Method marks are awarded for correct steps.

Fix: Show every step. Write formulae. Substitute. Answer. Especially for “show that” and “hence”.

Quadratic and equation solving

For equations, show method—factorisation, formula, completing the square. Answer alone is insufficient.

Fix: Quadratic formula with a, b, c substituted. Or factorise. Or complete the square.

Notation and presentation

Correct notation

Wrong or inconsistent notation. e.g. dx/dt vs. dy/dx; set notation; interval notation.

Fix: Use correct symbols. Practise past papers for notation.

Multiple attempts

When reattempting, clearly indicate which solution should be marked. Unclear scripts lose marks.

Fix: Cross out old work. Write “marked” or use a star on final attempt.

Common topic errors

Calculus

Chain rule, product rule, quotient rule—wrong application or omitted. Rates of change: dy/dt = dy/dx × dx/dt.

Fix: Identify rule needed. Write formula. Apply correctly.

Trigonometry

Wrong identities; wrong quadrant; degrees vs. radians. Check calculator mode.

Fix: sin²x + cos²x = 1. tan x = sin x / cos x. Radians for calculus.

Probability and statistics

Wrong distribution; wrong interpretation of “given that”; conditional probability formula.

Fix: P(A|B) = P(A∩B) / P(B). Identify distribution. Check “given” = conditional.

Reading questions

Not reading questions carefully. Missing “hence”, “show that”, “exact value”, “to 3 significant figures”.

Fix: Underline key words. “Hence” = use previous part. “Exact” = surds, π, etc.

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Based on Pearson Edexcel International A-level Mathematics Principal Examiner Feedback and common patterns.