Geometrical Reasoning and Proof: Edexcel 4MA1 Past Paper Questions and Worked Solutions
This page collects every geometrical reasoning and proof question from the Pearson Edexcel International GCSE Mathematics A (4MA1) Higher tier Paper 1H and Paper 1HR, January 2020 to June 2025: 3 questions worth 9 marks. Questions run from easier to harder. Try each one first, then click “Show solution” for a step-by-step method with the reason for every step. All answers are checked against the official Pearson mark schemes.
Using algebra, prove that, given any 3 consecutive whole numbers, the sum of the square of the smallest number and the square of the largest number is always 2 more than twice the square of the middle number.
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- Let the numbers be n − 1, n and n + 1 (so n is the middle number).
- (n − 1)2 + (n + 1)2 = n2 − 2n + 1 + n2 + 2n + 1 = 2n2 + 2
- 2n2 + 2 is 2 more than twice the square of the middle number.
Answer: (n − 1)2 + (n + 1)2 = 2n2 + 2
Using algebra, prove that, given any 3 consecutive even numbers, the difference between the square of the largest number and the square of the smallest number is always 8 times the middle number.
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- Let the three consecutive even numbers be 2n, 2n + 2 and 2n + 4, where n is an integer.
- (2n + 4)2 − (2n)2 = 4n2 + 16n + 16 − 4n2 = 16n + 16
- Factorise: 16n + 16 = 8(2n + 2), and 2n + 2 is the middle number.
Answer: (2n + 4)2 − (2n)2 = 8(2n + 2), which is 8 × the middle number
Prove that, for any three numbers which are consecutive multiples of 4, the difference between the square of the largest number and the square of the smallest number is always a multiple of 64. Show clear algebraic working.
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- Let the three consecutive multiples of 4 be 4n, 4n + 4 and 4n + 8, where n is an integer.
- Square of the largest: (4n + 8)2 = 16n2 + 64n + 64
- Square of the smallest: (4n)2 = 16n2
- Difference: 16n2 + 64n + 64 − 16n2 = 64n + 64
- Factorise: 64n + 64 = 64(n + 1). Since n + 1 is an integer, this is always a multiple of 64.
Answer: (4n + 8)2 − (4n)2 = 64(n + 1), a multiple of 64
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