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0580/32 Oct/Nov 2022, Question 8: Quadratic Graphs and the Parabola

Cambridge IGCSE Mathematics 0580 · Paper 32 (Core) · Calculator · 12 marks

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The question, in short

Complete a table for y = x² + 2x − 4, plot and sketch its graph from x = −5 to 3, find the line of symmetry, solve x² + 2x − 4 = 0 graphically, and find a parallel line.

Summarised in our own words. Use the official paper for the exact wording and the diagram.

Part (ai) · 3 marks

Fill in the missing y-values in the table for y = x² + 2x − 4 at the given x-values.

  1. 1x = −4: 16 − 8 − 4 = 4; x = −2: 4 − 4 − 4 = −4
  2. 2x = −1: 1 − 2 − 4 = −5; x = 0: −4
  3. 3x = 2: 4 + 4 − 4 = 4

Answer| x | −4 | −2 | −1 | 0 | 2 | | y | 4 | −4 | −5 | −4 | 4 |

Part (aii) · 4 marks

Plot the graph of y = x² + 2x − 4 on the grid for x from −5 to 3.

  1. 1Plot (−5, 11), (−4, 4), (−3, −1), (−2, −4), (−1, −5), (0, −4), (1, −1), (2, 4), (3, 11)
  2. 2Join with a smooth U-shaped curve, lowest point at (−1, −5)

AnswerCorrect curve

Part (aiii) · 1 mark

Sketch the curve for −5 ≤ x ≤ 3 and state the equation of its line of symmetry.

  1. 1Symmetric pairs, e.g. y(−3) = y(1) = −1, around x = −1
  2. 2x = −1

Answerx = −1

Part (aiv) · 2 marks

Use your drawn graph to find the solutions of x² + 2x − 4 = 0.

  1. 1Read where the curve crosses y = 0 (the x-axis)
  2. 2x ≈ −3.2 and x ≈ 1.2

Answerx = −3.3 to −3.1, x = 1.1 to 1.3

Part (b) · 2 marks

Find the equation of the line parallel to y = 5x + 7 that passes through (0, −2).

  1. 1Parallel: same gradient 5; through (0, −2): c = −2
  2. 2y = 5x − 2

Answery = 5x − 2

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Also searched as: 0580/32/O/N/22 · 0580_w22_qp_32 · 0580 w22 32 · question 8.
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