ECZ 2018 · GCE Paper 2 · Question 12 — Graphs of Functions

Question from ECZ 2018 · GCE Paper 2 · Question 12

(a) Express 32x - 5 - 4x - 3 as a single fraction in its lowest terms.[3]

Verified working — step 1

Common denominator (2x - 5)(x - 3).

(b) The diagram below shows the graph of y = x3 + x2 - 12x.

Diagram for part (b)

(b(i)) Use the graph to solve the equations

(b(i)(a)) x3 + x2 - 12x = 0,[2]

Verified working — step 1

The solutions are where the curve crosses the x-axis (y = 0).

(b(i)(b)) x3 + x2 - 12x = x + 10.[3]

Verified working — step 1

The solutions are where the curve meets the line y = x + 10.

(b(ii)) Calculate an estimate of the

(b(ii)(a)) gradient of the curve at the point where x = -3,[2]

Verified working — step 1

The point is (-3, 18), since (-3)3 + (-3)2 - 12(-3) = 18.

(b(ii)(b)) area bounded by the curve, x = -3, x = -1 and y = -10.[2]

Verified working — step 1

Measure each curve height ABOVE y = -10 (height = y + 10) at x = -3, -2.5, -2, -1.5, -1: 28, 30.6, 30, 26.9, 22.

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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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