f: x → (2x+3)² for x > 0
- (a)Find the range of f.[1]
- (b)Explain why f has an inverse.[1]
- (c)Find f⁻¹.[3]
- (d)State the domain of f⁻¹.[1]
- (e)Given that g: x → ln(x+4) for x > 0, find the exact solution of fg(x) = 49.[3]
Mark scheme
Marking points from the official mark scheme (May/June 2020). The mark or mark type is shown in brackets.
- [1] f > 9
- [1] It is a one-one function because of the restricted domain
- [1] For a correct attempt to find the inverse
- [1] For correct rearrangement
- [1] Must have correct notation
- [1] x > 9
- [1] For correct order
- [1] For correct attempt to solve, dep on previous M mark, as far as x =
- [1] x = e²-4
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