Q1 · Difficulty 1/3
The function f(x) = 2x + 3 is defined for all real numbers. What is the inverse function f⁻¹(x)?
- f⁻¹(x) = (x - 3)/2
- f⁻¹(x) = (x + 3)/2
- f⁻¹(x) = 2x - 3
- f⁻¹(x) = x/2 - 3
Show answer & explanation
✓ Answer: A — f⁻¹(x) = (x - 3)/2
Award 1 mark for correct inverse. Let y = 2x + 3, then x = (y - 3)/2, so f⁻¹(x) = (x - 3)/2. B is incorrect — this adds 3 instead of subtracting. C is incorrect — this reverses operations in wrong order. D is incorrect — this subtracts 3 after dividing instead of before.