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

For (a), let:

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