ECZ 2016 · O-Level Paper 1 — Relations and Functions
Given that f(x) = (5x + 4)⁄5, find f⁻¹(x).
- A. 5⁄(5x + 4)
- B. (5x + 4)⁄5
- C. (5x − 4)⁄5
- D. (x − 4)⁄5
Verified working — step 1
The inverse undoes f - a rearrangement, never a reciprocal. Set y = f(x), make x the subject, then swap the letters.The full step-by-step working and final answer, plus the video lesson for this topic, 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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