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O-LevelAdditional MathematicsPermutations and combinations4037/12 · Oct/Nov 2025 · Q113 Marks

Solve the equation (n-4) n+1C5 = n+2C7.

Solve the equation (n-4) n+1C5 = n+2C7.[3]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.

[3] B1 for 7×6 or 42 seen as a result of simplification of the numerical factorials
B1 for n+2 seen as a result of simplification of the algebraic factorials
B1 n=40

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About this question

Topic: Permutations and combinations, O-Level Additional Mathematics (syllabus 4037). Structured question, 3 marks.
Source: O-Level Additional Mathematics, Oct/Nov 2025 Paper 1 Variant 2, question 11.

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