ECZ 2023 · O-Level Paper 2 · Question 10 — Graphs of Functions

Question from ECZ 2023 · O-Level Paper 2 · Question 10

(a) The values of x and y are connected by the equation y = x3 - 9x + 5. Some of the corresponding values of x and y are given in the table below. x-3.5-3-2-10122.533.5y-6.45q135-3-5-1.9516.4

(a(i)) Calculate the value of q.[1]

Verified working — step 1

q is the curve's y-value at x = -2:

(a(ii)) Using a scale of 2 cm to represent 1 unit on the x-axis and 2 cm to represent 5 units on the y-axis for -4 ≤ x ≤ 4 and -10 ≤ y ≤ 20, draw the graph of y = x3 - 9x + 5.[3]

Verified working — step 1

Plot the table's points: (-3, 5), (-2, 15), (-1, 13), …

(a(iii)) Use your graph to find the solutions of the equations

(a(iii)(a)) x3 - 9x + 5 = 0,[2]

Verified working — step 1

The solutions of x3 - 9x + 5 = …

(a(iii)(b)) x3 - 9x + 5 = -3x + 6.[3]

Verified working — step 1

The equation says curve = line, so draw y = -3x + 6 through (0, 6) and (2, 0).

(b) Evaluate ∫2-1 (3x2 - 2x + 1) dx.[3]

Verified working — step 1

Integrate term by term: antiderivative x3 - x2 + x.

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Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.

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