Quadratic Equations: Edexcel 4MA1 Past Paper Questions and Worked Solutions
This page collects every quadratic equations question from the Pearson Edexcel International GCSE Mathematics A (4MA1) Higher tier Paper 1H and Paper 1HR, January 2020 to June 2025: 8 questions worth 36 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.
Solve x2 − 5x − 36 = 0. Show clear algebraic working.
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- Two numbers that multiply to −36 and add to −5: −9 and +4.
- (x − 9)(x + 4) = 0
Answer: x = 9 or x = −4
(a) Expand and simplify (x + 4)(x − 2)(x + 1) (3)
(b) Express x2 − 10x + 40 in the form (x + a)2 + b, where a and b are integers. (2)
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Part (a)
- (x + 4)(x − 2) = x2 + 2x − 8
- (x2 + 2x − 8)(x + 1) = x3 + x2 + 2x2 + 2x − 8x − 8
Answer: x3 + 3x2 − 6x − 8
Part (b)
- Half of −10 is −5: x2 − 10x = (x − 5)2 − 25
- (x − 5)2 − 25 + 40
Answer: (x − 5)2 + 15
ABCED is a five-sided shape. ABCD is a rectangle with AB = x cm and BC = y cm. CED is an equilateral triangle on top of the rectangle. The perimeter of ABCED is 100 cm. The area of ABCED is R cm2.
(a) Show that R = x4(200 − [6 − √3]x) (3)
(b)(i) Find the value of x for which R has its maximum value. Give your answer in the form pq − √3 where p and q are integers. (2)
(ii) Explain why the maximum value of R is given by this value of x. (1)
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Part (a)
- The perimeter goes AB + BC + CE + ED + DA = x + y + x + x + y = 3x + 2y = 100, so y = 100 − 3x2
- Area of the rectangle = xy = x(100 − 3x)2 = x4(200 − 6x)
- Area of an equilateral triangle with side x = ½x2 sin 60° = √34x2 = x4(√3x)
- R = x4(200 − 6x) + x4(√3x) = x4(200 − 6x + √3x)
Answer: R = x4(200 − [6 − √3]x)
Part (b)(i)
- Expand: R = 50x − 6 − √34x2
- At the maximum, dRdx = 0: 50 − 6 − √32x = 0
- x = 1006 − √3
Answer: x = 1006 − √3
Part (b)(ii)
- R is a quadratic in x with a negative x2 coefficient (6 − √3 is positive, so −6 − √34 is negative). Its graph is an upside-down U, so the turning point is a maximum.
Answer: The x2 coefficient is negative, so the stationary point is a maximum
(a) Express 7 + 12x − 3x2 in the form a + b(x + c)2 where a, b and c are integers. (3)
C is the curve with equation y = 7 + 12x − 3x2. The point A is the maximum point on C.
(b) Use your answer to part (a) to write down the coordinates of A. (1)
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Part (a)
- Take out −3 from the x terms: 7 − 3(x2 − 4x)
- Complete the square: x2 − 4x = (x − 2)2 − 4
- 7 − 3[(x − 2)2 − 4] = 7 + 12 − 3(x − 2)2
Answer: 19 − 3(x − 2)2, so a = 19, b = −3, c = −2
Part (b)
- −3(x − 2)2 is never positive, so y is largest (19) when x = 2.
Answer: (2, 19)
(a) Express 2x2 − 11x + 9 in the form a(x − b)2 − c where a, b and c are numbers to be found. (3)
The curve C has equation y = 2(x − 3)2 − 11(x − 3) + 9. The point P is the minimum point on C.
(b) Find the coordinates of P. (2)
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Part (a)
- Take out the factor 2 from the x terms: 2[x2 − 112x] + 9
- Complete the square: x2 − 112x = (x − 114)2 − (114)2 = (x − 114)2 − 12116
- So 2[(x − 114)2 − 12116] + 9 = 2(x − 114)2 − 1218 + 9
- −1218 + 9 = −1218 + 728 = −498
Answer: 2(x − 2.75)2 − 6.125, i.e. a = 2, b = 114, c = 498
Part (b)
- From part (a), y = 2x2 − 11x + 9 has its minimum at (2.75, −6.125).
- The equation of C is the same expression with x replaced by (x − 3). That is a translation 3 units to the right.
- P = (2.75 + 3, −6.125)
Answer: (5.75, −6.125)
(a) Express 2x2 − 12x + 3 in the form a(x + b)2 + c where a, b and c are integers. (3)
The curve C has equation y = 2(x + 4)2 − 12(x + 4) + 3. The point M is the minimum point on C.
(b) Find the coordinates of M. (2)
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Part (a)
- Take out 2 from the x terms: 2(x2 − 6x) + 3
- Complete the square: x2 − 6x = (x − 3)2 − 9
- 2[(x − 3)2 − 9] + 3 = 2(x − 3)2 − 18 + 3
Answer: 2(x − 3)2 − 15
Part (b)
- y = 2x2 − 12x + 3 has its minimum at (3, −15).
- C is the same curve with x replaced by (x + 4), which is a translation 4 units to the left.
Answer: (−1, −15)
Express each of a, b and c in terms of q so that q + 12x − qx2 can be written as a − b(x − c)2
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- Take out −q from the x terms: q − q(x2 − 12qx)
- Complete the square: x2 − 12qx = (x − 6q)2 − 36q2
- q − q[(x − 6q)2 − 36q2] = q + 36q − q(x − 6q)2
- Compare with a − b(x − c)2.
Answer: a = q + 36q, b = q, c = 6q
f(x) = 17 − 3x2 + 12x. Write f(x) in the form a − b(x − c)2 where a, b and c are constants.
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- Group the x terms and take out −3: f(x) = 17 − 3(x2 − 4x)
- Complete the square inside the bracket: x2 − 4x = (x − 2)2 − 4
- f(x) = 17 − 3[(x − 2)2 − 4] = 17 − 3(x − 2)2 + 12
- Combine the numbers: 17 + 12 = 29
Answer: 29 − 3(x − 2)2
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