ECZ 2021 · GCE Paper 1 — Quadratic Functions
The diagram shows a sketch of the graph of y = 5 − 4x − x². Find the maximum value of y.
- A. 5
- B. −2
- C. 9
- D. 21
Verified working — step 1
Write y = −(x² + 4x) + 5 = −(x + 2)² + 4 + 5 = −(x + 2)² + 9. The squared term is never negative, so y is greatest when x = …The full step-by-step working and final answer are included with Premium — checked against ECZ marking standards.
Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.
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