ECZ 2025 · O-Level Paper 1 — Relations and Functions
The functions f and g are defined as f(x) = 2x + 1 and g(x) = 3x - 2, x ≠ 2. Find: (a) f-1(x), (b) gf(x), (c) gf(-2).
- A. (a) f-1(x) = 1 - x2 (b) gf(x) = 32x - 3 (c) gf(-2) = 3-2
- B. (a) f-1(x) = 2x - 1 (b) gf(x) = 3x - 1 (c) gf(-2) = -1
- C. (a) f-1(x) = x + 12 (b) gf(x) = 32x + 1 (c) gf(-2) = 35
- D. (a) f-1(x) = x - 12 (b) gf(x) = 32x - 1, x ≠ 12 (c) gf(-2) = -35
Verified working — step 1
Three jobs on the same pair of functions. For the inverse: swap x and y, then solve for y. For gf(x): apply f first, then feed the whole result into g.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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